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Krambrich J, Akaberi D, Lindahl JF, Lundkvist Å, Hesson JC. Vector competence of Swedish Culex pipiens mosquitoes for Japanese encephalitis virus. Parasit Vectors 2024; 17:220. [PMID: 38741172 DOI: 10.1186/s13071-024-06269-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 04/02/2024] [Indexed: 05/16/2024] Open
Abstract
BACKGROUND Japanese encephalitis virus (JEV) is an emerging mosquito-borne Orthoflavivirus that poses a significant public health risk in many temperate and tropical regions in Asia. Since the climate in some endemic countries is similar to temperate climates observed in Europe, understanding the role of specific mosquito species in the transmission of JEV is essential for predicting and effectively controlling the potential for the introduction and establishment of JEV in Europe. METHODS This study aimed to investigate the vector competence of colonized Culex pipiens biotype molestus mosquitoes for JEV. The mosquitoes were initially collected from the field in southern Sweden. The mosquitoes were offered a blood meal containing the Nakayama strain of JEV (genotype III), and infection rates, dissemination rates, and transmission rates were evaluated at 14, 21, and 28 days post-feeding. RESULTS The study revealed that colonized Swedish Cx. pipiens are susceptible to JEV infection, with a stable infection rate of around 10% at all timepoints. However, the virus was only detected in the legs of one mosquito at 21 days post-feeding, and no mosquito saliva contained JEV. CONCLUSIONS Overall, this research shows that Swedish Cx. pipiens can become infected with JEV, and emphasizes the importance of further understanding of the thresholds and barriers for JEV dissemination in mosquitoes.
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Affiliation(s)
- Janina Krambrich
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, Husargatan 3, 75237, Uppsala, Sweden.
| | - Dario Akaberi
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, Husargatan 3, 75237, Uppsala, Sweden
| | - Johanna F Lindahl
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, Husargatan 3, 75237, Uppsala, Sweden
- International Livestock Research Institute, Hanoi, Vietnam
- Department of Animal Health and Antibiotic Strategies, Swedish National Veterinary Institute, Uppsala, Sweden
| | - Åke Lundkvist
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, Husargatan 3, 75237, Uppsala, Sweden
| | - Jenny C Hesson
- Zoonosis Science Center, Department of Medical Biochemistry and Microbiology, Uppsala University, Husargatan 3, 75237, Uppsala, Sweden
- Biologisk Myggkontroll, Nedre Dalälvens Utvecklings AB, Gysinge, Sweden
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Chiou SS, Chen JM, Chen YY, Chia MY, Fan YC. The feasibility of field collected pig oronasal secretions as specimens for the virologic surveillance of Japanese encephalitis virus. PLoS Negl Trop Dis 2021; 15:e0009977. [PMID: 34860839 PMCID: PMC8673640 DOI: 10.1371/journal.pntd.0009977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 12/15/2021] [Accepted: 11/05/2021] [Indexed: 11/24/2022] Open
Abstract
Virologic surveillance of Japanese encephalitis virus (JEV) relies on collecting pig blood specimens and adult mosquitoes in the past. Viral RNAs extracted from pig blood specimens suffer from low detecting positivity by reverse transcription PCR (RT-PCR). The oronasal transmission of the virus has been demonstrated in experimentally infected pigs. This observation suggested oronasal specimens could be useful source in the virus surveillance. However, the role of this unusual route of transmission remains unproven in the operational pig farm. In this study, we explore the feasibility of using pig oronasal secretions collected by chewing ropes to improve the positivity of detection in commercial pig farms. The multiplex genotype-specific RT-PCR was used in this study to determine and compare the positivity of detecting JEV viral RNAs in pig’s oronasal secretions and blood specimens, and the primary mosquito vector. Oronasal specimens had the overall positive rate of 6.0% (95% CI 1.3%–16.6%) (3/50) to 10.0% (95% CI 2.1%–26.5%) (3/30) for JEV during transmission period despite the negative results of all blood-derived specimens (n = 2442). Interestingly, pig oronasal secretions and female Culex tritaeniorhynchus mosquito samples collected from the same pig farm showed similar viral RNA positive rates, 10.0% (95% CI 2.1%–26.5%) (3/30) and 8.9% (95% CI 2.5%–21.2%) (4/45), respectively (p> 0.05). Pig oronasal secretion-based surveillance revealed the seasonality of viral activity and identified closely related genotype I virus derived from the mosquito isolates. This finding indicates oronasal secretion-based RT-PCR assay can be a non-invasive, alternative method of implementing JEV surveillance in the epidemic area prior to the circulation of virus-positive mosquitoes. Mosquito-borne Japanese encephalitis virus (JEV) has either endemic or seasonal patterns of transmission in Asia and Australia. Most hosts infected by the virus remains asymptomatic but can result in severe encephalitis in humans and horses, and abortion or stillbirth in pregnant sows. Isolation of virus in adult mosquitoes or pig seroconversion has been used as an early indicator of upcoming JE outbreak in humans. Genotype identification of the virus is important since current human and domestic animal vaccines are all genotype III (GIII) specific. GIII vaccine elicited immunity has reduced cross-protections to genotypes other than GIII. Our virologic surveillance using pig’s oronasal secretion detected higher prevalence and earlier genotype I virus activity than using pig’s blood and mosquitoes, respectively. This proposed surveillance tool might be more effective that will allow the public health agency to properly implement the preventive measures, such as implementing mosquito control, encouraging booster vaccination, and encouraging the use of mosquito repellent, to reduce the impact of upcoming outbreak. Collection of pig’s oronasal secretion is non-invasive to pigs and less technically demanding to operators. Thus we propose the use of pig’s oronasal secretions as the novel source of specimens for virologic surveillance to replace the traditional pig blood or adult mosquito specimens to monitor and control JE outbreak/epidemic in the future.
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Affiliation(s)
- Shyan-Song Chiou
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Jo-Mei Chen
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Yi-Ying Chen
- Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Min-Yuan Chia
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Yi-Chin Fan
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan
- * E-mail:
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Moore SM. The current burden of Japanese encephalitis and the estimated impacts of vaccination: Combining estimates of the spatial distribution and transmission intensity of a zoonotic pathogen. PLoS Negl Trop Dis 2021; 15:e0009385. [PMID: 34644296 PMCID: PMC8544850 DOI: 10.1371/journal.pntd.0009385] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 10/25/2021] [Accepted: 09/20/2021] [Indexed: 11/18/2022] Open
Abstract
Japanese encephalitis virus (JEV) is a major cause of neurological disability in Asia and causes thousands of severe encephalitis cases and deaths each year. Although Japanese encephalitis (JE) is a WHO reportable disease, cases and deaths are significantly underreported and the true burden of the disease is not well understood in most endemic countries. Here, we first conducted a spatial analysis of the risk factors associated with JE to identify the areas suitable for sustained JEV transmission and the size of the population living in at-risk areas. We then estimated the force of infection (FOI) for JE-endemic countries from age-specific incidence data. Estimates of the susceptible population size and the current FOI were then used to estimate the JE burden from 2010 to 2019, as well as the impact of vaccination. Overall, 1,543.1 million (range: 1,292.6-2,019.9 million) people were estimated to live in areas suitable for endemic JEV transmission, which represents only 37.7% (range: 31.6-53.5%) of the over four billion people living in countries with endemic JEV transmission. Based on the baseline number of people at risk of infection, there were an estimated 56,847 (95% CI: 18,003-184,525) JE cases and 20,642 (95% CI: 2,252-77,204) deaths in 2019. Estimated incidence declined from 81,258 (95% CI: 25,437-273,640) cases and 29,520 (95% CI: 3,334-112,498) deaths in 2010, largely due to increases in vaccination coverage which have prevented an estimated 314,793 (95% CI: 94,566-1,049,645) cases and 114,946 (95% CI: 11,421-431,224) deaths over the past decade. India had the largest estimated JE burden in 2019, followed by Bangladesh and China. From 2010-2019, we estimate that vaccination had the largest absolute impact in China, with 204,734 (95% CI: 74,419-664,871) cases and 74,893 (95% CI: 8,989-286,239) deaths prevented, while Taiwan (91.2%) and Malaysia (80.1%) had the largest percent reductions in JE burden due to vaccination. Our estimates of the size of at-risk populations and current JE incidence highlight countries where increasing vaccination coverage could have the largest impact on reducing their JE burden. Japanese encephalitis is a vector-transmitted, zoonotic disease that is endemic throughout a large portion of Asia. Vaccination has significantly reduced the JE burden in several formerly high-burden countries, but vaccination coverage remains limited in several other countries with high JE burdens. A better understanding of both the spatial distribution and the magnitude of the burden in endemic countries is critical for future disease prevention efforts. To estimate the number of people living in areas within Asia suitable for JEV transmission we conducted a spatial analysis of the risk factors associated with JE. We estimate that over one billion people live in areas suitable for local JEV transmission. We then combined these population-at-risk estimates with estimates of the force of infection (FOI) to model the national-level burden of JE (annual cases and deaths) over the past decade. Increases in vaccination coverage have reduced JE incidence from over 80,000 cases in 2010 to fewer than 57,000 cases in 2019. We estimate that vaccination has prevented almost 315,000 cases and 115,000 deaths in the past decade. Our results also call attention to the countries, and high-risk areas within countries, where increases in vaccination coverage are most needed.
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Affiliation(s)
- Sean M. Moore
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
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Auerswald H, Maquart PO, Chevalier V, Boyer S. Mosquito Vector Competence for Japanese Encephalitis Virus. Viruses 2021; 13:v13061154. [PMID: 34208737 PMCID: PMC8234777 DOI: 10.3390/v13061154] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/02/2021] [Accepted: 06/02/2021] [Indexed: 12/30/2022] Open
Abstract
Japanese encephalitis virus (JEV) is a zoonotic pathogen mainly found in East and Southeast Asia and transmitted by mosquitoes. The objective of this review is to summarize the knowledge on the diversity of JEV mosquito vector species. Therefore, we systematically analyzed reports of JEV found in field-caught mosquitoes as well as experimental vector competence studies. Based on the investigated publications, we classified 14 species as confirmed vectors for JEV due to their documented experimental vector competence and evidence of JEV found in wild mosquitoes. Additionally, we identified 11 mosquito species, belonging to five genera, with an experimentally confirmed vector competence for JEV but lacking evidence on their JEV transmission capacity from field-caught mosquitoes. Our study highlights the diversity of confirmed and potential JEV vector species. We also emphasize the variety in the study design of vector competence investigations. To account for the diversity of the vector species and regional circumstances, JEV vector competence should be studied in the local context, using local mosquitoes with local virus strains under local climate conditions to achieve reliable data. In addition, harmonization of the design of vector competence experiments would lead to better comparable data, informing vector and disease control measures.
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Affiliation(s)
- Heidi Auerswald
- Virology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh 120210, Cambodia
- Correspondence:
| | - Pierre-Olivier Maquart
- Medical and Veterinary Entomology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh 120210, Cambodia; (P.-O.M.); (S.B.)
| | - Véronique Chevalier
- Epidemiology and Public Health Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh 120210, Cambodia;
- UMR ASTRE, CIRAD, INRA, Université de Montpellier, 34000 Montpellier, France
| | - Sebastien Boyer
- Medical and Veterinary Entomology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh 120210, Cambodia; (P.-O.M.); (S.B.)
- Institut Pasteur, 75015 Paris, France
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Tu T, Xu K, Xu L, Gao Y, Zhou Y, He Y, Liu Y, Liu Q, Ji H, Tang W. Association between meteorological factors and the prevalence dynamics of Japanese encephalitis. PLoS One 2021; 16:e0247980. [PMID: 33657174 PMCID: PMC7928514 DOI: 10.1371/journal.pone.0247980] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 02/17/2021] [Indexed: 12/29/2022] Open
Abstract
Japanese encephalitis (JE) is an acute infectious disease caused by the Japanese encephalitis virus (JEV) and is transmitted by mosquitoes. Meteorological conditions are known to play a pivotal role in the spread of JEV. In this study, a zero-inflated generalised additive model and a long short-term memory model were used to assess the relationship between the meteorological factors and population density of Culex tritaeniorhynchus as well as the incidence of JE and to predict the prevalence dynamics of JE, respectively. The incidence of JE in the previous month, the mean air temperature and the average of relative humidity had positive effects on the outbreak risk and intensity. Meanwhile, the density of all mosquito species in livestock sheds (DMSL) only affected the outbreak risk. Moreover, the region-specific prediction model of JE was developed in Chongqing by used the Long Short-Term Memory Neural Network. Our study contributes to a better understanding of the JE dynamics and helps the local government establish precise prevention and control measures.
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Affiliation(s)
- Taotian Tu
- Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China
| | - Keqiang Xu
- College of Computer and Information Engineering, Henan Normal University, Xinxiang, Henan Province, China
| | - Lei Xu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- Department of Earth System Science, Ministry of Education Key Laboratory for Earth System Modeling, Tsinghua University, Beijing, China
| | - Yuan Gao
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ying Zhou
- Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China
| | - Yaming He
- Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China
| | - Yang Liu
- Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China
| | - Qiyong Liu
- State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Hengqing Ji
- Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China
- * E-mail: (WT); (HJ)
| | - Wenge Tang
- Chongqing Municipal Center for Disease Control and Prevention, Chongqing, China
- * E-mail: (WT); (HJ)
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Hameed M, Wahaab A, Nawaz M, Khan S, Nazir J, Liu K, Wei J, Ma Z. Potential Role of Birds in Japanese Encephalitis Virus Zoonotic Transmission and Genotype Shift. Viruses 2021; 13:357. [PMID: 33668224 PMCID: PMC7996159 DOI: 10.3390/v13030357] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/15/2021] [Accepted: 02/20/2021] [Indexed: 12/13/2022] Open
Abstract
Japanese encephalitis (JE) is a vaccine-preventable disease caused by the Japanese encephalitis virus (JEV), which is primarily prevalent in Asia. JEV is a Flavivirus, classified into a single serotype with five genetically distinct genotypes (I, II, III, IV, and V). JEV genotype III (GIII) had been the most dominant strain and caused numerous outbreaks in the JEV endemic countries until 1990. However, recent data shows the emergence of JEV genotype I (GI) as a dominant genotype and it is gradually displacing GIII. The exact mechanism of this genotype displacement is still unclear. The virus can replicate in mosquito vectors and vertebrate hosts to maintain its zoonotic life cycle; pigs and aquatic wading birds act as an amplifying/reservoir hosts, and the humans and equines are dead-end hosts. The important role of pigs as an amplifying host for the JEV is well known. However, the influence of other domestic animals, especially birds, that live in high abundance and close proximity to the human is not well studied. Here, we strive to briefly highlight the role of birds in the JEV zoonotic transmission, discovery of birds as a natural reservoirs and amplifying host for JEV, species of birds susceptible to the JEV infection, and the proposed effect of JEV on the poultry industry in the future, a perspective that has been neglected for a long time. We also discuss the recent in vitro and in vivo studies that show that the newly emerged GI viruses replicated more efficiently in bird-derived cells and ducklings/chicks than GIII, and an important role of birds in the JEV genotype shift from GIII to GI.
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Affiliation(s)
- Muddassar Hameed
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China; (A.W.); (M.N.); (S.K.); (K.L.)
| | - Abdul Wahaab
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China; (A.W.); (M.N.); (S.K.); (K.L.)
| | - Mohsin Nawaz
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China; (A.W.); (M.N.); (S.K.); (K.L.)
| | - Sawar Khan
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China; (A.W.); (M.N.); (S.K.); (K.L.)
| | - Jawad Nazir
- Vaccinologist/Head Virology, Tréidlia Biovet Pty Ltd. Units, Seven Hills, NSW 2147, Australia;
| | - Ke Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China; (A.W.); (M.N.); (S.K.); (K.L.)
| | - Jianchao Wei
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China; (A.W.); (M.N.); (S.K.); (K.L.)
| | - Zhiyong Ma
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai 200241, China; (A.W.); (M.N.); (S.K.); (K.L.)
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Faizah AN, Kobayashi D, Amoa-Bosompem M, Higa Y, Tsuda Y, Itokawa K, Miura K, Hirayama K, Sawabe K, Isawa H. Evaluating the competence of the primary vector, Culex tritaeniorhynchus, and the invasive mosquito species, Aedes japonicus japonicus, in transmitting three Japanese encephalitis virus genotypes. PLoS Negl Trop Dis 2020; 14:e0008986. [PMID: 33370301 PMCID: PMC7793266 DOI: 10.1371/journal.pntd.0008986] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 01/08/2021] [Accepted: 11/12/2020] [Indexed: 01/13/2023] Open
Abstract
Japanese encephalitis virus (JEV) is maintained in an enzootic cycle between swine, water birds, and mosquitoes. JEV has circulated indigenously in Asia, with Culex tritaeniorhynchus as the primary vector. In some areas where the primary vector is scarce or absent, sporadic cases of Japanese encephalitis have been reported, with Aedes japonicus japonicus presumed to have the potential as a secondary vector. As one of the world's most invasive culicid species, Ae. j. japonicus carries a considerable health risk for spreading diseases to wider areas, including Europe and North America. Thus, evaluation of its competency as a JEV vector, particularly in a native population, will be essential in preventing potential disease spread. In this study, the two mosquito species' vector competence in transmitting three JEV genotypes (I, III, and V) was assessed, with Cx. tritaeniorhynchus serving as a point of reference. The mosquitoes were virus-fed and the infection rate (IR), dissemination rate (DR), and transmission rate (TR) evaluated individually by either RT-qPCR or focus forming assay. Results showed striking differences between the two species, with IR of 95% (261/274) and 9% (16/177) in Cx. tritaeniorhynchus and Ae. j. japonicus, respectively. Both mosquitoes were susceptible to all three JEV genotypes with significant differences in IR and mean viral titer. Results confirm the primary vector's competence, but the fact that JEV was able to establish in Ae. j. japonicus is of public health significance, and with 2%-16% transmission rate it has the potential to successfully transmit JEV to the next host. This may explain the human cases and infrequent detection in primary vector-free areas. Importantly, Ae. j. japonicus could be a relevant vector spreading the disease into new areas, indicating the need for security measures in areas where the mosquito is distributed or where it may be introduced.
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Affiliation(s)
- Astri Nur Faizah
- Laboratory of Veterinary Public Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan
- Department of Medical Entomology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Daisuke Kobayashi
- Department of Medical Entomology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Michael Amoa-Bosompem
- Department of Medical Entomology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
- Department of Environmental Parasitology, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Yukiko Higa
- Department of Medical Entomology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Yoshio Tsuda
- Department of Medical Entomology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Kentaro Itokawa
- Pathogen Genomics Center, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Kozue Miura
- Laboratory of Veterinary Public Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan
| | - Kazuhiro Hirayama
- Laboratory of Veterinary Public Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan
| | - Kyoko Sawabe
- Department of Medical Entomology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Haruhiko Isawa
- Department of Medical Entomology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
- * E-mail:
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Liu K, Xiao C, Xi S, Hameed M, Wahaab A, Shao D, Li Z, Li B, Wei J, Qiu Y, Miao D, Zhu H, Ma Z. Mosquito Defensins Enhance Japanese Encephalitis Virus Infection by Facilitating Virus Adsorption and Entry within the Mosquito. J Virol 2020; 94:e01164-20. [PMID: 32796073 PMCID: PMC7565626 DOI: 10.1128/jvi.01164-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/02/2020] [Indexed: 12/11/2022] Open
Abstract
Japanese encephalitis virus (JEV) is a viral zoonosis that can cause viral encephalitis, death, and disability. Although the Culex mosquito is the primary vector of JEV, little is known about JEV transmission by this kind of mosquito. Here, we found that mosquito defensin facilitated the adsorption of JEV on target cells via the defensin/lipoprotein receptor-related protein 2 (LRP2) axis. Mosquito defensin bound the ED III domain of the viral envelope (E) protein and directly mediated efficient virus adsorption on the target cell surface; the receptor LRP2, which is expressed on the cell surface, affected defensin-dependent adsorption. As a result, mosquito defensin enhanced JEV infection in the salivary gland, increasing the possibility of viral transmission by mosquitoes. These findings demonstrate the novel role of mosquito defensin in JEV infection and the mechanisms through which the virus exploits mosquito defensin for infection and transmission.IMPORTANCE In this study, we observed the complex roles of mosquito defensin in JEV infection; mosquito defensin exhibited a weak antiviral effect but strongly enhanced binding. In the latter, defensin directly binds the ED III domain of the viral E protein and promotes the adsorption of JEV to target cells by interacting with lipoprotein receptor-related protein 2 (LRP2), thus accelerating virus entry. Together, our results indicate that mosquito defensin plays an important role in facilitating JEV infection and potential transmission.
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Affiliation(s)
- Ke Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Changguang Xiao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Shumin Xi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Muddassar Hameed
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Abdul Wahaab
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Donghua Shao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Zongjie Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Beibei Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Jianchao Wei
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Yafeng Qiu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
| | - Denian Miao
- Institute of Animal Husbandry and Veterinary Science, Shanghai Academy of Agricultural Sciences, Shanghai, People's Republic of China
| | - Huaimin Zhu
- Department of Pathogen Biology, Second Military Medical University, Shanghai, People's Republic of China
| | - Zhiyong Ma
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, People's Republic of China
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Ghosh SK, Podder D, Panja AK, Mukherjee S. In target areas where human mosquito-borne diseases are diagnosed, the inclusion of the pre-adult mosquito aquatic niches parameters will improve the integrated mosquito control program. PLoS Negl Trop Dis 2020; 14:e0008605. [PMID: 32797109 PMCID: PMC7449462 DOI: 10.1371/journal.pntd.0008605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 08/26/2020] [Accepted: 07/15/2020] [Indexed: 11/19/2022] Open
Abstract
In human communities inhabiting areas-such as West Bengal- India-where perpetuate the pre-imago & adult developmental stages of mosquitoes; many infectious diseases are still diagnosed such as Dengue, Malaria and Acute Encephalitis Syndrome. The control of the aquatic developmental stages is one of the easiest way to prevent the emergence of adults-the blood feeding adult females being thus prevented to sample their blood meal and to lay their eggs in the aquatic milieu where develop the aquatic pre-imaginal developmental stages. Moreover, reducing the adult population size also the probability of for the blood feeding adult female mosquitoes to act as hosts and vectors of the arboviruses such as dengue virus & Japanese encephalitis virus as well as of Plasmodium. Several environmental factors including water quality parameters are responsible for the selection of oviposition sites by the female mosquitoes. In our study, larval densities of three important mosquitoes (Aedes/A. albopictus, Anopheles/An. stephensi and Culex/C. vishnui) were measured and water qualities of their habitat i.e. pH, Specific Conductance, Dissolved Oxygen, Chemical Oxygen Demand, Total alkalinity (Talk), Hardness, Nitrate nitrogen and Ammonia nitrogen were analyzed in 2017 and 2018 in many districts of West Bengal where humans beings are suffering from arboviruses and /or malaria. Whereas we have found positive correlation of density of C. vishnui and A. albopictus with the water factors except Chemical Oxygen Demand (COD) and Talk, for An. stephensi all these factors except pH, COD and Talk have positive correlation. Hardness of the water shows positive correlation with the density of An. stephensi and C. vishnui but negative correlation with density of A. albopictus. Contour plot analysis demonstrates that occurrence of each mosquito species lies in between specific range of water factors. Inter- correlation analysis revealed that mosquitoes were negatively correlated with each other. A positive correlation of the water quality parameters and larval density, over two successive years, was also noticed. In conclusion, the increasing level of pollution due to industrial and other irresponsible waste management system which changes the water quality parameters may also influence mosquito population.
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Affiliation(s)
- Swapan Kumar Ghosh
- Molecular mycopathology lab, Biological Control and Cancer Research Unit, PG Department of Botany, Ramakrishna Mission Vivekananda Centenary College (Autonomous), Rahara, Kolkata, WB, India
- * E-mail:
| | - Dipanjan Podder
- Molecular mycopathology lab, Biological Control and Cancer Research Unit, PG Department of Botany, Ramakrishna Mission Vivekananda Centenary College (Autonomous), Rahara, Kolkata, WB, India
| | - Atanu Kumar Panja
- Molecular mycopathology lab, Biological Control and Cancer Research Unit, PG Department of Botany, Ramakrishna Mission Vivekananda Centenary College (Autonomous), Rahara, Kolkata, WB, India
| | - Sabyasachi Mukherjee
- Molecular mycopathology lab, Biological Control and Cancer Research Unit, PG Department of Botany, Ramakrishna Mission Vivekananda Centenary College (Autonomous), Rahara, Kolkata, WB, India
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10
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Mileno MD. Japanese Encephalitis Vaccine. R I Med J (2013) 2020; 103:49-50. [PMID: 32752568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Travelers to 24 endemic countries in Asia may be at risk for Japanese encephalitis. The ACIP has recently expanded guidelines on the use of Ixiaro, the inactivated Japanese encephalitis vaccine. This article reviews the disease burden of Japanese encephalitis and the role of a travel clinic in guiding travelers to Asia regarding decision-making about the use of this highly protective vaccine.
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Affiliation(s)
- Maria D Mileno
- Associate Professor of Medicine, Division of Infectious Diseases, Alpert Medical School of Brown University, Providence, RI
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11
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Ladreyt H, Durand B, Dussart P, Chevalier V. How Central Is the Domestic Pig in the Epidemiological Cycle of Japanese Encephalitis Virus? A Review of Scientific Evidence and Implications for Disease Control. Viruses 2019; 11:E949. [PMID: 31618959 PMCID: PMC6832429 DOI: 10.3390/v11100949] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/04/2019] [Accepted: 10/11/2019] [Indexed: 11/17/2022] Open
Abstract
Despite the existence of human vaccines, Japanese encephalitis (JE) remains the leading cause of human encephalitis in Asia. Pigs are described as the main amplifying host, but their role in JE epidemiology needs to be reassessed in order to identify and implement efficient control strategies, for both human and animal health. We aimed to provide a systematic review of publications linked to JE in swine, in terms of both individual and population characteristics of JE virus (JEV) infection and circulation, as well as observed epidemiological patterns. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement to select and analyze relevant articles from the Scopus database, 127 of which were included in the review. Pigs are central, but the implication of secondary hosts cannot be ruled out and should be further investigated. Although human vaccination cannot eradicate the virus, it is clearly the most important means of preventing human disease. However, a better understanding of the actual involvement of domestic pigs as well as other potential JEV hosts in different JEV epidemiological cycles and patterns could help to identify additional/complementary control measures, either by targeting pigs or not, and in some specific epidemiological contexts, contribute to reduce virus circulation and protect humans from JEV infection.
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Affiliation(s)
- Héléna Ladreyt
- Epidemiology Unit, Laboratory for Animal Health, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), University Paris-Est, 94700 Maisons-Alfort, France.
- Agricultural Research for Development (CIRAD), UMR ASTRE, F-34090 Montpellier, France.
| | - Benoit Durand
- Epidemiology Unit, Laboratory for Animal Health, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), University Paris-Est, 94700 Maisons-Alfort, France.
| | - Philippe Dussart
- Virology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, PO Box 983, Phnom Penh 12201, Cambodia.
| | - Véronique Chevalier
- Agricultural Research for Development (CIRAD), UMR ASTRE, F-34090 Montpellier, France.
- Epidemiology and Public Health Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, PO Box 983, Phnom Penh 12201, Cambodia.
- Agricultural Research for Development (CIRAD), UMR ASTRE, Phnom Penh 12201, Cambodia.
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12
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Hameed M, Liu K, Anwar MN, Wahaab A, Safdar A, Di D, Boruah P, Xu J, Wang X, Li B, Zhu H, Nawaz M, Shao D, Qiu Y, Wei J, Ma Z. The emerged genotype I of Japanese encephalitis virus shows an infectivity similar to genotype III in Culex pipiens mosquitoes from China. PLoS Negl Trop Dis 2019; 13:e0007716. [PMID: 31557156 PMCID: PMC6762057 DOI: 10.1371/journal.pntd.0007716] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 08/16/2019] [Indexed: 12/14/2022] Open
Abstract
Japanese Encephalitis virus (JEV) is a zoonotic flavivirus that represents the most significant etiology of childhood viral neurological infections throughout the Asia. During the last 20 years, JEV genotype dominance has shifted from genotype III (GIII) to genotype I (GI). To date, the exact mechanism of this displacement is still not known. Culex (Cx.) mosquitoes are the most common species in China and play an essential role in maintaining JEV enzootic transmission cycle. In this study, we used Cx. pipiens mosquitoes from China as an in vivo mosquito model to explore if mosquitoes played a potential role in JEV genotype shift. We exposed female Cx. pipiens mosquitoes orally to either GI or GIII JEV strains. Midgut, whole mosquitoes, secondary organs, and salivary glands of JEV-infected mosquitoes were collected at 7 and 14 days of post infection (dpi) and subjected to measure the infection rate, replication kinetics, dissemination rate and transmission potential of the infected JEV strains in Cx. pipiens mosquitoes by 50% tissue culture infective dose assay. We found that Cx. pipiens mosquito was competent vector for both GI and GIII JEV infection, with similar infection rates and growth kinetics. After the establishment of infection, Cx. pipiens mosquitoes disseminated both JEV genotypes to secondary organs at similar rates of dissemination. A few GI-infected mosquito salivary glands (16.2%) were positive for GI virus, whereas GIII virus was undetectable in GIII-infected mosquito salivary glands at 7 dpi. However, 29.4% (5/17) and 36.3% (8/22) were positive for GI- and GIII-infected mosquito salivary glands at 14 dpi, respectively, showing an increase in JEV positive rate. No statistical difference in the transmission rate between GI- and GIII-infected mosquitoes was detected. Our experiment data demonstrated that GI and GIII viruses have similar infectivity in Cx. pipiens mosquitoes, suggesting that Cx. pipiens mosquitoes from China may not play a critical role in JEV genotype shift. Although the current data were obtained solely from Cx. pipiens mosquitoes, it is likely that the conclusion drawn could be extrapolated to the role of mosquitoes in JEV genotype shift.
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Affiliation(s)
- Muddassar Hameed
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Ke Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Muhammad Naveed Anwar
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Abdul Wahaab
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Anum Safdar
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Di Di
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Prerona Boruah
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Jinpeng Xu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Xin Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Beibei Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Huaimin Zhu
- Department of Pathogen biology, Second Military Medical University, Shanghai, PR China
| | - Mohsin Nawaz
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Donghua Shao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Yafeng Qiu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Jianchao Wei
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
| | - Zhiyong Ma
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Science, Shanghai, PR China
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13
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Sahu SS, Sonia T, Dash S, Gunasekaran K, Jambulingam P. Insecticide resistance status of three vectors of Japanese encephalitis in east central India. Med Vet Entomol 2019; 33:213-219. [PMID: 30565276 DOI: 10.1111/mve.12352] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/10/2018] [Accepted: 11/01/2018] [Indexed: 06/09/2023]
Abstract
Japanese encephalitis (JE) has been reported in different districts of Odisha state (east central India) since 1992. During 2016, a major outbreak of JE and acute encephalitis syndrome (AES) occurred in the Malkangiri district of Odisha, causing 103 deaths in children, of which 37 were caused by JE and 66 by AES. Information on insecticide resistance in JE vectors is important for the selection of appropriate insecticides for use in vector control. The present study was designed to determine the resistance status of three important vectors of JE, Culex vishnui, Culex tritaeniorhynchus and Culex bitaeniorhynchus (Diptera: Culicidae), against dichlorodiphenyltrichloroethane (DDT), malathion and deltamethrin in three districts of Odisha state affected by JE. Female adult mosquitoes were collected using mouth aspirators both indoors and outdoors in JE-affected villages and used in susceptibility bioassays following World Health Organization guidelines. Knock-downs were recorded every 10 min up to 1 h and mortality rates were recorded at 24 h post-exposure. Culex vishnui and Cx. tritaeniorhynchus showed resistance to DDT, malathion and deltamethrin, whereas Cx. bitaeniorhynchus was susceptible in all study districts. The information generated by this study will be highly useful in the planning and implementing of appropriate vector control operations for the prevention and control of JE in east central India.
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Affiliation(s)
- S S Sahu
- Vector Control Research Centre, Indian Council of Medical Research, Medical Complex, Indira Nagar, Puducherry, India
| | - T Sonia
- Vector Control Research Centre, Indian Council of Medical Research, Medical Complex, Indira Nagar, Puducherry, India
| | - S Dash
- Vector Control Research Centre, Indian Council of Medical Research, Medical Complex, Indira Nagar, Puducherry, India
| | - K Gunasekaran
- Vector Control Research Centre, Indian Council of Medical Research, Medical Complex, Indira Nagar, Puducherry, India
| | - P Jambulingam
- Vector Control Research Centre, Indian Council of Medical Research, Medical Complex, Indira Nagar, Puducherry, India
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14
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Chai C, Palinski R, Xu Y, Wang Q, Cao S, Geng Y, Zhao Q, Wen Y, Huang X, Yan Q, Ma X, Wen X, Huang Y, Han X, Ma W, Wu R. Aerosol and Contact Transmission Following Intranasal Infection of Mice with Japanese Encephalitis Virus. Viruses 2019; 11:v11010087. [PMID: 30669601 PMCID: PMC6356382 DOI: 10.3390/v11010087] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 01/08/2019] [Accepted: 01/18/2019] [Indexed: 12/30/2022] Open
Abstract
The Japanese encephalitis virus (JEV), a causative agent of severe viral encephalitis in humans, has a biological cycle fluctuating between transmission in mosquitoes and avian species and amplification in pigs. Contact transmission of JEV was recently shown in pigs in the absence of arthropod vectors. Here, we show JEV transmission between infected and contact mice and further demonstrate that JEV transmission occurs between animals via aerosols, as both viral RNA and infectious JEV were detected in direct contact- and aerosol-exposed contact animals. The results of this study change our understanding of JEV transmission in densely populated regions and may help to explain JEV outbreaks without the presence of arthropod vectors.
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Affiliation(s)
- Chunxia Chai
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Rachel Palinski
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
| | - Yixuan Xu
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Qiao Wang
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Sanjie Cao
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Yi Geng
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Qin Zhao
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Yiping Wen
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Xiaobo Huang
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Qiguai Yan
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Xiaoping Ma
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Xintian Wen
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Yong Huang
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Xinfeng Han
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
| | - Wenjun Ma
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
| | - Rui Wu
- Research Center of Swine Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China.
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15
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Liu MD, Li CX, Huang Y, Dong YD, Nu W, Zhao TY. Spatial Distribution of Culex tritaeniorhynchus Giles, 1901 (Diptera: Culicidae) in Relation to Pigsties and Other Geo-environmental Features in Dao County, Hunan Province, China. J Med Entomol 2019; 56:241-246. [PMID: 30169709 DOI: 10.1093/jme/tjy135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Indexed: 06/08/2023]
Abstract
In this study, we investigated the spatial distribution of Culex tritaeniorhynchus Giles, 1901 (Diptera: Culicidae) (the vector of Japanese B Encephalitis) and geo-environmental features (rice fields, forests, watercourses, and highways) correlated with their abundance in pigsties of Dao County, Hunan Province, China. First, light trapping in pigsties was carried out to determine vector density. Second, based on Advanced Land Observing Satellite remote-sensing datasets, spatial datasets of mosquito density and various geo-environmental features were constructed using Geography Information System. Finally, spatial statistical analysis and general linear regression were used to analyze the spatial distribution of vectors in relation to the geo-environmental features correlating with the abundance of mosquitoes in pigsties. As the results show, the distribution of mosquitoes in pigsties was not spatially autocorrelated, and several geo-environmental features that were either positively or negatively correlated with mosquito abundance in pigsties were identified. The application of these results to improve the control of vectors of Japanese B Encephalitis is also discussed.
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Affiliation(s)
- M D Liu
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing, China
| | - C X Li
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing, China
| | - Y Huang
- Hunan Center for Disease Control and Prevention, Changsha, China
| | - Y D Dong
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing, China
| | - W Nu
- Hunan Center for Disease Control and Prevention, Changsha, China
| | - T Y Zhao
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing, China
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16
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Abstract
Mosquito-borne diseases have become more common as previously geographically isolated diseases have spread globally. Chikungunya, dengue, Japanese encephalitis, malaria, West Nile, yellow fever, and Zika are a few of the common and emerging viral diseases spread by mosquitoes. A thorough patient history, physical, and knowledge of diagnostic testing based on symptom duration is important to make a quick and accurate diagnosis. Because the treatment for many of these diseases is supportive, the emphasis is on reducing risk and spread of infection.
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Affiliation(s)
- Hobart Lee
- Department of Family Medicine, Loma Linda University School of Medicine, 1200 California Street, Suite 240, Redlands, CA 92374, USA.
| | - Sara Halverson
- Department of Family Medicine, Loma Linda University School of Medicine, 1200 California Street, Suite 240, Redlands, CA 92374, USA
| | - Ngozi Ezinwa
- Department of Family Medicine, Loma Linda University School of Medicine, 1200 California Street, Suite 240, Redlands, CA 92374, USA
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17
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Liu B, Gao X, Ma J, Jiao Z, Xiao J, Wang H. Influence of Host and Environmental Factors on the Distribution of the Japanese Encephalitis Vector Culex tritaeniorhynchus in China. Int J Environ Res Public Health 2018; 15:ijerph15091848. [PMID: 30150565 PMCID: PMC6165309 DOI: 10.3390/ijerph15091848] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 08/23/2018] [Accepted: 08/25/2018] [Indexed: 12/16/2022]
Abstract
Culex tritaeniorhynchus is an important vector that transmits a variety of human and animal diseases. Japanese encephalitis (JE), an endemic disease in the Asia-Pacific region, is primarily transmitted by Cx. tritaeniorhynchus. Insufficient monitoring of vector mosquitoes has led to a poor understanding of the distribution of Cx. tritaeniorhynchus in China. To delineate the habitat of Cx. tritaeniorhynchus and any host and environmental factors that affect its distribution, we used a maximum entropy modeling method to predict its distribution in China. Our models provided high resolution predictions on the potential distribution of Cx. tritaeniorhynchus. The predicted suitable habitats of the JE vector were correlated with areas of high JE incidence in parts of China. Factors driving the distribution of Cx. tritaeniorhynchus in China were also revealed by our models. Furthermore, human population density and the maximum NDVI were the most important predictors in our models. Bioclimate factors and elevation also significantly impacted the distribution of Cx. tritaeniorhynchus. Our findings may serve as a reference for vector and disease control.
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Affiliation(s)
- Boyang Liu
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
| | - Xiang Gao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
| | - Jun Ma
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
| | - Zhihui Jiao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
| | - Jianhua Xiao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
| | - Hongbin Wang
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, China.
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18
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Karthika P, Vadivalagan C, Thirumurugan D, Kumar RR, Murugan K, Canale A, Benelli G. DNA barcoding of five Japanese encephalitis mosquito vectors (Culex fuscocephala, Culex gelidus, Culex tritaeniorhynchus, Culex pseudovishnui and Culex vishnui). Acta Trop 2018; 183:84-91. [PMID: 29625090 DOI: 10.1016/j.actatropica.2018.04.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 03/17/2018] [Accepted: 04/01/2018] [Indexed: 12/25/2022]
Abstract
Culex mosquitoes can act as vectors of several important diseases, including Japanese encephalitis, West Nile virus, St. Louis encephalitis and equine encephalitis. Besides the neurological sequelae caused in humans, Japanese encephalitis can lead to abortion in sows and encephalitis in horses. Effective vector control and early diagnosis, along with continuous serosurveillance in animals, are crucial to fight this arboviral disease. However, the success of vector control operations is linked with the fast and reliable identification of targeted species, and knowledge about their biology and ecology. Since the DNA barcoding of Culex vectors of Japanese encephalitis is scarcely explored, here we evaluated the efficacy of this tool to identify and analyze the variations among five overlooked Culex vectors of Japanese encephalitis, Culex fuscocephala, Culex gelidus, Culex tritaeniorhynchus, Culex pseudovishnui and Culex vishnui, relying to the analysis of mitochondrial CO1 gene. Variations in their base pair range were elucidated by the entropy Hx plot. The differences among individual conspecifics and on base pair range across the same were studied. The C (501-750 bp) region showed a moderate variation among all the selected species. C. tritaeniorhynchus exhibited the highest variation in all the ranges. The observed genetic divergence was partially non-discriminatory. i.e., the overall intra- and inter nucleotide divergence was 0.0920 (0.92%) and 0.125 (1.25%), respectively. However, 10X rule fits accurately intraspecies divergence <3% for the five selected Culex species. The analysis of individual scatter plots showed threshold values (10X) of 0.008 (0.08%), 0.005 (0.05%), 0.123 (1.23%), 0.033 (0.33%) and 0.019 (0.19%) for C. fuscocephala, C. gelidus, C. tritaeniorhynchus, C. pseudovishnui and C. vishnui, respectively. The C. tritaeniorhynchus haplotypes KU497604, KU497603, AB690847 and AB690854 exhibited the highest divergence range, i.e., from 0.465 -0.546. Comparatively, the intra-divergence among the other haplotypes of C. tritaeniorhynchus ranged from 0-0.056. The maximum parsimony tree was formed by distinctive conspecific clusters with appreciable branch values illustrating their close congruence and extensive genetic deviations. Overall, this study adds valuable knowledge to the molecular biology and systematics of five overlooked mosquito species acting as major vectors of Japanese encephalitis in Asian countries.
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Affiliation(s)
- Pushparaj Karthika
- Department of Zoology, Avinashilingam Institute for Home Science and Higher Education for Women, Coimbatore 641 043, Tamil Nadu, India
| | - Chithravel Vadivalagan
- Department of Biotechnology, SRM Institute of Science and Technology, Kattankulathur, Chennai, Tamil Nadu 603203, India; Entomology Laboratory, Department of Zoology, Bharathiar University, Coimbatore, 641046, Tamil Nadu, India.
| | - Durairaj Thirumurugan
- Department of Biotechnology, SRM Institute of Science and Technology, Kattankulathur, Chennai, Tamil Nadu 603203, India
| | - Rangaswamy Ravi Kumar
- Centre for Medical Entomology and Vector Control, National Center for Disease Control, M/o Health and Family Welfare, Govt. of India, 22-Shamnath Marg, Delhi, 110054, India
| | - Kadarkarai Murugan
- Entomology Laboratory, Department of Zoology, Bharathiar University, Coimbatore, 641046, Tamil Nadu, India; Department of Biotechnology, Thiruvalluvar University, Serkkadu, Vellore 632 115, Tamil Nadu, India
| | - Angelo Canale
- Department of Agriculture, Food and Environment, University of Pisa, via del Borghetto 80, 56124 Pisa, Italy
| | - Giovanni Benelli
- Department of Agriculture, Food and Environment, University of Pisa, via del Borghetto 80, 56124 Pisa, Italy; The BioRobotics Institute, Sant'Anna School of Advanced Studies, viale Rinaldo Piaggio 34, 56025 Pontedera, Pisa, Italy.
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19
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Zhang H, Rehman MU, Li K, Luo H, Lan Y, Nabi F, Zhang L, Iqbal MK, Zhu S, Javed MT, Chamba Y, Li JK. Epidemiologic Survey of Japanese Encephalitis Virus Infection, Tibet, China, 2015. Emerg Infect Dis 2018; 23:1023-1024. [PMID: 28518046 PMCID: PMC5443422 DOI: 10.3201/eid2306.152115] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We investigated Japanese encephalitis virus (JEV) prevalence in high-altitude regions of Tibet, China, by using standard assays to test mosquitoes, pigs, and humans. Results confirmed that JEV has spread to these areas. Disease prevention and control strategies should be used along with surveillance to limit spread of JEV in high-altitude regions of Tibet.
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Bae W, Kim JH, Kim J, Lee J, Hwang ES. Changes of Epidemiological Characteristics of Japanese Encephalitis Viral Infection and Birds as a Potential Viral Transmitter in Korea. J Korean Med Sci 2018; 33:e70. [PMID: 29441740 PMCID: PMC5811662 DOI: 10.3346/jkms.2018.33.e70] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/27/2017] [Indexed: 11/20/2022] Open
Abstract
Japanese encephalitis (JE) cases have been increasingly reported recently especially in Seoul and its vicinity. Pigs are known as amplifying host of JE virus (JEV), but do not play an important role in these recent events because pig-breeding is not common in Seoul. The distribution and the density of migratory birds are correlated with JE cases in cities and they might be highly potential hosts contributing to transmit JEV in metropolitan areas. JE genotype and sero-prevalence in birds should be determined for the verification of the transmission route of JEV in the recent sporadic occurrence of JE cases in Seoul.
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Affiliation(s)
- Wonjun Bae
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Korea
- Global Center for Infectious Diseases, Seoul National University College of Medicine, Seoul, Korea
| | - Jung Heon Kim
- Global Center for Infectious Diseases, Seoul National University College of Medicine, Seoul, Korea
- Institute of Endemic Disease, Seoul National University Medical Research Center, Seoul, Korea
| | - Jiyeon Kim
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Korea
- Global Center for Infectious Diseases, Seoul National University College of Medicine, Seoul, Korea
| | - Jungyun Lee
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Korea
- Global Center for Infectious Diseases, Seoul National University College of Medicine, Seoul, Korea
| | - Eung Soo Hwang
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Korea
- Global Center for Infectious Diseases, Seoul National University College of Medicine, Seoul, Korea
- Institute of Endemic Disease, Seoul National University Medical Research Center, Seoul, Korea.
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Cheng VCC, Sridhar S, Wong SC, Wong SCY, Chan JFW, Yip CCY, Chau CH, Au TWK, Hwang YY, Yau CSW, Lo JYC, Lee CK, Yuen KY. Japanese Encephalitis Virus Transmitted Via Blood Transfusion, Hong Kong, China. Emerg Infect Dis 2018; 24. [PMID: 29043965 PMCID: PMC5749455 DOI: 10.3201/eid2401.171297] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Japanese encephalitis virus (JEV) is a mosquitoborne virus endemic to China and Southeast Asia that causes severe encephalitis in <1% of infected persons. Transmission of JEV via blood transfusion has not been reported. We report transmission of JEV via blood donation products from an asymptomatic viremic donor to 2 immunocompromised recipients. One recipient on high-dose immunosuppressive drugs received JEV-positive packed red blood cells after a double lung transplant; severe encephalitis and a poor clinical outcome resulted. JEV RNA was detected in serum, cerebrospinal fluid, and bronchoalveolar lavage fluid specimens. The second recipient had leukemia and received platelets after undergoing chemotherapy. This patient was asymptomatic; JEV infection was confirmed in this person by IgM seroconversion. This study illustrates that, consistent with other pathogenic flaviviruses, JEV can be transmitted via blood products. Targeted donor screening and pathogen reduction technologies could be used to prevent transfusion-transmitted JEV infection in highly JEV-endemic areas.
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Tangena JAA, Thammavong P, Lindsay SW, Brey PT. Risk of exposure to potential vector mosquitoes for rural workers in Northern Lao PDR. PLoS Negl Trop Dis 2017; 11:e0005802. [PMID: 28742854 PMCID: PMC5544251 DOI: 10.1371/journal.pntd.0005802] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 08/04/2017] [Accepted: 07/12/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND One major consequence of economic development in South-East Asia has been a rapid expansion of rubber plantations, in which outbreaks of dengue and malaria have occurred. Here we explored the difference in risk of exposure to potential dengue, Japanese encephalitis (JE), and malaria vectors between rubber workers and those engaged in traditional forest activities in northern Laos PDR. METHODOLOGY/PRINCIPAL FINDINGS Adult mosquitoes were collected for nine months in secondary forests, mature and immature rubber plantations, and villages. Human behavior data were collected using rapid participatory rural appraisals and surveys. Exposure risk was assessed by combining vector and human behavior and calculating the basic reproduction number (R0) in different typologies. Compared to those that stayed in the village, the risk of dengue vector exposure was higher for those that visited the secondary forests during the day (odds ratio (OR) 36.0), for those living and working in rubber plantations (OR 16.2) and for those that tapped rubber (OR 3.2). Exposure to JE vectors was also higher in the forest (OR 1.4) and, similar when working (OR 1.0) and living in the plantations (OR 0.8). Exposure to malaria vectors was greater in the forest (OR 1.3), similar when working in the plantations (OR 0.9) and lower when living in the plantations (OR 0.6). R0 for dengue was >2.8 for all habitats surveyed, except villages where R0≤0.06. The main malaria vector in all habitats was Anopheles maculatus s.l. in the rainy season and An. minimus s.l. in the dry season. CONCLUSIONS/SIGNIFICANCE The highest risk of exposure to vector mosquitoes occurred when people visit natural forests. However, since rubber workers spend long periods in the rubber plantations, their risk of exposure is increased greatly compared to those who temporarily enter natural forests or remain in the village. This study highlights the necessity of broadening mosquito control to include rubber plantations.
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Affiliation(s)
- Julie-Anne A. Tangena
- Department of Medical Entomology & Biology of Disease Vectors, Institut Pasteur du Laos, Vientiane, Lao PDR
- School of Biological and Biomedical Sciences, Durham University, Durham, United Kingdom
- * E-mail:
| | - Phoutmany Thammavong
- Department of Medical Entomology & Biology of Disease Vectors, Institut Pasteur du Laos, Vientiane, Lao PDR
| | - Steve W. Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, United Kingdom
| | - Paul T. Brey
- Department of Medical Entomology & Biology of Disease Vectors, Institut Pasteur du Laos, Vientiane, Lao PDR
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23
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Tuno N, Tsuda Y, Takagi M. How Zoophilic Japanese Encephalitis Vector Mosquitoes Feed on Humans. J Med Entomol 2017; 54:8-13. [PMID: 28082626 DOI: 10.1093/jme/tjw165] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/12/2016] [Indexed: 06/06/2023]
Abstract
Japanese encephalitis virus (JEV) is the most frequent cause of mosquito-borne encephalitis in Asian countries. Several culicine species are potential vectors. The primary JEV vectors feed mainly on cows (a dead-end host for JEV), pigs (an amplifying host), and, occasionally, humans (a dead-end host). It is essential to determine blood-feeding patterns to understand the transmission cycle of the disease. Here we review blood-feeding characteristics of the primary JEV vectors Culex tritaeniorhynchus, Culex vishnui, and Culex gelidus based on experimental works and field surveys conducted in Asian countries. Several studies showed that these JEV vectors have an innate preference for cows; however, the former two species often showed higher rates of blood-feeding on pigs than on cows, probably because pigs are more abundant than cows. On the other hand, the latter species Cx. gelidus fed mostly on cows. Thus, the first two species showed higher plasticity to compromise host availability than the last. By reviewing the available articles and based on our relevant studies, it may be deduced that JEV transmission cannot be reduced by zooprophylaxis. We emphasize the need of keeping cows away from the human residences to dampen the human risk of JEV. These primary JEV vector species exhibit pre-biting resting. The adaptive significance of this behavior remains to be unexplored, but it may have a function to avoid defensive attack of host animals. Application of recent quantitative analysis of gene expression in this phase may enable us to come up with novel vector control strategies.
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Affiliation(s)
- N Tuno
- Graduate School of Natural Science and Technology, Kanazawa University, Ishikawa 920-1192, Japan
| | - Y Tsuda
- Department of Medical Entomology, National Institute of Infectious Diseases, Tokyo 162-8640
| | - M Takagi
- Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523
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24
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Kim HC, Kim MS, Choi KS, Hwang DU, Johnson JL, Klein TA. Comparison of Adult Mosquito Black-Light and Light-Emitting Diode Traps at Three Cowsheds Located in Malaria-Endemic Areas of the Republic of Korea. J Med Entomol 2017; 54:221-228. [PMID: 28082650 DOI: 10.1093/jme/tjw136] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/02/2016] [Indexed: 06/06/2023]
Abstract
Adult mosquito surveillance and field trials evaluated selected commercially available ultraviolet black-light (BL) and light-emitting diode (LED) traps at three sites where vivax malaria is endemic from May to October 2015 in northwestern Republic of Korea. Collections totaled 283,929 adult mosquitoes (280,355 [98.74%] females and 3,574 [1.26%] males) comprising 17 species (including six members of the Anopheles Hyrcanus Group) belonging to six genera. The four most predominant female species collected were Aedes vexans nipponii (Theobald) (83.84%), followed by Anopheles Hyrcanus Group (13.66%), Culex pipiens Group (1.67%), and Culex tritaeniorhynchus Giles (0.54%). Overall, LED traps (188,125) collected significantly more female mosquitoes compared with BL traps (92,230; P = 0.0001, P < 0.05). Results from these field evaluations significantly enhance vector and disease surveillance efforts, especially for the primary vectors of malaria (Anopheles Hyrcanus Group) and Japanese encephalitis (Cx. tritaeniorhynchus).
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Affiliation(s)
- Heung-Chul Kim
- 5th Medical Detachment, 168th Multifunctional Medical Battalion 65 Medical Brigade, Unit 15247, APO AP, 96205-5247 (; ; )
| | - Myung-Soon Kim
- 5th Medical Detachment, 168th Multifunctional Medical Battalion 65 Medical Brigade, Unit 15247, APO AP, 96205-5247 (; ; )
| | - Kwang-Shik Choi
- College of Natural Science, Kyungpook National University, Daegu 41566, Republic of Korea (; )
| | - Do-Un Hwang
- College of Natural Science, Kyungpook National University, Daegu 41566, Republic of Korea (; )
| | - Jaree L Johnson
- 5th Medical Detachment, 168th Multifunctional Medical Battalion 65 Medical Brigade, Unit 15247, APO AP, 96205-5247 (; ; )
| | - Terry A Klein
- MEDDAC-K/65th Medical Brigade, Unit 15281, APO AP 96205-5281
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25
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Govindarajan M, Benelli G. Eco-friendly larvicides from Indian plants: Effectiveness of lavandulyl acetate and bicyclogermacrene on malaria, dengue and Japanese encephalitis mosquito vectors. Ecotoxicol Environ Saf 2016; 133:395-402. [PMID: 27504617 DOI: 10.1016/j.ecoenv.2016.07.035] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 07/23/2016] [Accepted: 07/25/2016] [Indexed: 06/06/2023]
Abstract
Mosquitoes (Diptera: Culicidae) are a key threat for millions of people and animals worldwide, since they act as vectors for devastating pathogens and parasites, including malaria, dengue, Japanese encephalitis, filiariasis and Zika virus. Mosquito young instars are usually targeted using organophosphates, insect growth regulators and microbial agents. Indoor residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have negative effects on human health and the environment and induce resistance in a number of vectors. In this scenario, newer and safer tools have been recently implemented to enhance mosquito control. The concrete potential of screening plant species as sources of metabolites for entomological and parasitological purposes is worthy of attention, as recently elucidated by the Y. Tu's example. Here we investigated the toxicity of Heracleum sprengelianum (Apiaceae) leaf essential oil and its major compounds toward third instar larvae of the malaria vector Anopheles subpictus, the arbovirus vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. GC-MS analysis showed that EO major components were lavandulyl acetate (17.8%) and bicyclogermacrene (12.9%). The EO was toxic to A. subpictus, A. albopictus, and C. tritaeniorhynchus, with LC50 of 33.4, 37.5 and 40.9µg/ml, respectively. Lavandulyl acetate was more toxic to mosquito larvae if compared to bicyclogermacrene. Their LC50 were 4.17 and 10.3µg/ml for A. subpictus, 4.60 and 11.1µg/ml for A. albopictus, 5.11 and 12.5µg/ml for C. tritaeniorhynchus. Notably, the EO and its major compounds were safer to three non-target mosquito predators, Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 ranging from 206 to 4219µg/ml. Overall, this study highlights that H. sprengelianum EO is a promising source of eco-friendly larvicides against three important mosquito vectors with moderate toxicity against non-target aquatic organisms.
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Affiliation(s)
- Marimuthu Govindarajan
- Unit of Vector Control, Phytochemistry and Nanotechnology, Department of Zoology, Annamalai University, Annamalainagar 608002, Tamil Nadu, India.
| | - Giovanni Benelli
- Insect Behavior Group, Department of Agriculture, Food and Environment, University of Pisa, via del Borghetto 80, 56124 Pisa, Italy.
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Wu ZM, Chu HL, Wang G, Zhu XJ, Guo XX, Zhang YM, Xing D, Yan T, Zhao MH, Dong YD, Li CX, Zhao TY. Multiple-Insecticide Resistance and Classic Gene Mutations to Japanese Encephalitis Vector Culex tritaeniorhynchus from China. J Am Mosq Control Assoc 2016; 32:144-151. [PMID: 27280353 DOI: 10.2987/moco-32-02-144-151.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Widespread resistance of insect pests to insecticides has been widely reported in China and there is consequently an urgent need to adjust pest management strategies appropriately. This requires detailed information on the extent and causes of resistance. The aim of the present study was to investigate levels of resistance to 5 insecticides among 12 strains of Culex tritaeniorhynchus, a major vector of Japanese encephalitis in China. Resistance to deltamethrin, beta-cypermethrin, permethrin, dichlorvos, and propoxur were measured using larval bioassays. The allelic frequency of knockdown resistance (kdr) and acetylcholinesterase (AChE) mutations were determined in all strains. Larval bioassay results indicated that the field strains collected from different sites were resistant to deltamethrin, beta-cypermethrin, permethrin, dichlorvos, and propoxur, with resistance ratio values ranging from 1.70- to 71.98-fold, 7.83- to 43.07-fold, 3.54- to 40.03-fold, 291.85- to 530.89-fold, and 51.32- to 108.83-fold, respectively. A polymerase chain reaction amplification of specific alleles method for individual was developed to detect genotypes of the AChE gene mutation F455W in Cx. tritaeniorhynchus. The frequency of the AChE gene mutation F455W was 100.00% in all strains, making this mutation of no value as a marker of resistance to organophosphorous and carbamate pesticides in Cx. tritaeniorhynchus in China. The kdr allele was present in all strains at frequencies of 10.00-29.55%. Regression analysis indicated a significant correlation between kdr allele frequencies and levels of resistance to deltamethrin, beta-cypermethrin, and permethrin. These results highlight the need to monitor and map insecticide resistance in Cx. tritaeniorhynchus and to adjust pesticide use to minimize the development of resistance in these mosquitoes.
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Affiliation(s)
- Zhi-Ming Wu
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
- 2 Anhui Medical University, Hefei 230032, China
| | - Hong-Liang Chu
- 3 Jiangsu Provincial Center for Disease Prevention and Control, Nanjing 210009, China
| | - Gang Wang
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Xiao-Juan Zhu
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
- 2 Anhui Medical University, Hefei 230032, China
| | - Xiao-Xia Guo
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Ying-Mei Zhang
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Dan Xing
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Ting Yan
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Ming-Hui Zhao
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
- 2 Anhui Medical University, Hefei 230032, China
| | - Yan-De Dong
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Chun-Xiao Li
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Tong-Yan Zhao
- 1 Department of Vector Biology and Control, State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Beijing 100071, China
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Lord JS, Al-Amin HM, Chakma S, Alam MS, Gurley ES, Pulliam JRC. Sampling Design Influences the Observed Dominance of Culex tritaeniorhynchus: Considerations for Future Studies of Japanese Encephalitis Virus Transmission. PLoS Negl Trop Dis 2016; 10:e0004249. [PMID: 26726881 PMCID: PMC4699645 DOI: 10.1371/journal.pntd.0004249] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 10/29/2015] [Indexed: 11/19/2022] Open
Abstract
Mosquito sampling during Japanese encephalitis virus (JEV)-associated studies, particularly in India, has usually been conducted via aspirators or light traps to catch mosquitoes around cattle, which are dead-end hosts for JEV. High numbers of Culex tritaeniorhynchus, relative to other species, have often been caught during these studies. Less frequently, studies have involved sampling outdoor resting mosquitoes. We aimed to compare the relative abundance of mosquito species between these two previously used mosquito sampling methods. From September to December 2013 entomological surveys were undertaken in eight villages in a Japanese encephalitis (JE) endemic area of Bangladesh. Light traps were used to collect active mosquitoes in households, and resting boxes and a Bina Pani Das hop cage were used near oviposition sites to collect resting mosquitoes. Numbers of humans and domestic animals present in households where light traps were set were recorded. In five villages Cx. tritaeniorhynchus was more likely to be selected from light trap samples near hosts than resting collection samples near oviposition sites, according to log odds ratio tests. The opposite was true for Cx. pseudovishnui and Armigeres subalbatus, which can also transmit JEV. Culex tritaeniorhynchus constituted 59% of the mosquitoes sampled from households with cattle, 28% from households without cattle and 17% in resting collections. In contrast Cx. pseudovishnui constituted 5.4% of the sample from households with cattle, 16% from households with no cattle and 27% from resting collections, while Ar. subalbatus constituted 0.15%, 0.38%, and 8.4% of these samples respectively. These observations may be due to differences in timing of biting activity, host preference and host-seeking strategy rather than differences in population density. We suggest that future studies aiming to implicate vector species in transmission of JEV should consider focusing catches around hosts able to transmit JEV. The relative numbers of individuals of each mosquito species in an area are important to estimate when identifying species that contribute the most to vector-borne pathogen transmission. However, methods to sample mosquitoes and enumerate the number of individuals collected often vary in their catch efficacy between species. For example, species that take a bloodmeal during daylight hours are less likely to be caught using a light trap than a species that feeds predominantly at night. Similarly, sampling near a mammalian host will more likely collect mosquitoes with a preference for mammals than those with a preference for birds. In this study we compare sampling methods for assessing the relative abundance of mosquito species that may be involved in Japanese encephalitis virus (JEV) transmission. Collections near cattle- a species unable to transmit JEV- have been influential in implicating Cx. tritaeniorhynchus as the primary vector of JEV in South Asia, due to the high number of individuals of this species caught relative to other species. Indeed, this mosquito constituted the majority of the mosquitoes collected by light traps in households with cattle in this study. However, other species were more common when sampling households without cattle or resting mosquitoes near oviposition sites. We propose that methods used to sample mosquitoes in studies aiming to implicate species in JEV transmission in South Asia be reconsidered given that there are other mosquito species that are able to transmit JEV, and these species may be underrepresented when sampling using light traps near cattle.
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Affiliation(s)
- Jennifer S. Lord
- Vector Group, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| | | | - Sumit Chakma
- Centre for Communicable Diseases, icddr,b, Mohakhali, Dhaka, Bangladesh
| | | | - Emily S. Gurley
- Centre for Communicable Diseases, icddr,b, Mohakhali, Dhaka, Bangladesh
| | - Juliet R. C. Pulliam
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
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Abstract
Japanese encephalitis (JE) is an inflammation of the central nervous system in humans and animals, specifically horses and cattle. The disease, which can sometimes be fatal, is caused by the flavivirus Japanese encephalitis virus (JEV), of which there are five genotypes (genotypes 1, 2, 3, 4 and 5). The transmission cycle of the virus involves pigs and wild birds as virus amplifiers and mosquitoes as vectors for transferring the virus between amplifying hosts and to dead- end hosts, i.e. humans, horses and cattle. In horses and cattle the disease is usually asymptomatic, but when clinical signs do occur they include fever, decreased appetite, frothing at the mouth, rigidity of the legs and recumbency, and neurological signs, such as convulsive fits, circling, marked depression and disordered consciousness. In pigs, it can cause abortion and stillbirths. At present, the virus is detected in a wide area covering eastern and southern Asia, Indonesia, northern Australia, Papua New Guinea and Pakistan. JEV RNA has also been detected in Italy, first in dead birds in 1997 and 2000 and then in mosquitoes in 2010. Genotype shift, i.e. a change of genotype from genotype 3 to genotype 1, has occurred in some countries, namely Japan, South Korea, Chinese Taipei and Vietnam. Laboratory methods are available for confirming the causative agent of the disease. There are control measures to prevent or minimise infection and, among them, vaccination is one of the most important and one which should be adopted in endemic and epidemic areas.
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29
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Govindarajan M, Rajeswary M, Veerakumar K, Muthukumaran U, Hoti SL, Benelli G. Green synthesis and characterization of silver nanoparticles fabricated using Anisomeles indica: Mosquitocidal potential against malaria, dengue and Japanese encephalitis vectors. Exp Parasitol 2015; 161:40-7. [PMID: 26708933 DOI: 10.1016/j.exppara.2015.12.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 11/30/2015] [Accepted: 12/14/2015] [Indexed: 11/19/2022]
Abstract
Mosquitoes (Diptera: Culicidae) represent a key threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. In this scenario, eco-friendly control tools against mosquito vectors are a priority. Green synthesis of silver nanoparticles (AgNP) using a cheap, aqueous leaf extract of Anisomeles indica by reduction of Ag(+) ions from silver nitrate solution has been investigated. Bio-reduced AgNP were characterized by UV-visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction analysis (XRD). The acute toxicity of A. indica leaf extract and biosynthesized AgNP was evaluated against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. Both the A. indica leaf extract and AgNP showed dose dependent larvicidal effect against all tested mosquito species. Compared to the leaf aqueous extract, biosynthesized AgNP showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 values of 31.56, 35.21 and 38.08 μg/mL, respectively. Overall, this study firstly shed light on the mosquitocidal potential of A. indica, a potential bioresource for rapid, cheap and effective AgNP synthesis.
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Affiliation(s)
- Marimuthu Govindarajan
- Unit of Vector Control, Phytochemistry and Nanotechnology, Department of Zoology, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India.
| | - Mohan Rajeswary
- Unit of Vector Control, Phytochemistry and Nanotechnology, Department of Zoology, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India
| | - Kaliyan Veerakumar
- Unit of Vector Control, Phytochemistry and Nanotechnology, Department of Zoology, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India
| | - Udaiyan Muthukumaran
- Unit of Vector Control, Phytochemistry and Nanotechnology, Department of Zoology, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India
| | - S L Hoti
- Regional Medical Research Centre, Nehru Nagar, Belgaum 590010, Karnataka, India
| | - Giovanni Benelli
- Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy
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30
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Affiliation(s)
- Jennifer S. Lord
- Vector Group, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| | - Emily S. Gurley
- Centre for Communicable Diseases, icddr,b, Mohakhali, Dhaka, Bangladesh
| | - Juliet R. C. Pulliam
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
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31
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Nyari N, Singh D, Kakkar K, Sharma S, Pandey SN, Dhole TN. Entomological and serological investigation of Japanese encephalitis in endemic area of eastern Uttar Pradesh, India. J Vector Borne Dis 2015; 52:321-328. [PMID: 26714513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023] Open
Abstract
BACKGROUND & OBJECTIVES Japanese encephalitis virus (JEV), a mosquito borne pathogen, is one of the major causes of viral encephalitis in eastern Uttar Pradesh, India. The objective of this work was to evaluate the entomological based virological surveillance of Japanese encephalitis (JE) in the highly endemic area of eastern Uttar Pradesh. METHODS The study was carried out during September 2010 to March 2013 in Gorakhpur district of Uttar Pradesh. A total of 251 adult mosquito pools and 64 water samples containing larvae were collected from the District of Gorakhpur. Water pH, turbidity, and oxygen level were analyzed for vector breeding index (BI). In addition, 393 serum/cerebrospinal fluid (CSF) samples of acute encephalitis syndrome (AES) suspected cases were collected from the district hospital. RESULTS The various Culex species found included, Cx. quinquefasciatus (26.83%), Cx. vishnui (22.29%), Cx. pseudovishnui (20.73%), Cx. tritaeniorhynchus (12.71%), Cx. whitmorei (9.04%), and Cx. gelidus (8.25%). Highest minimum infection rate (MIR) was calculated for Cx. tritaeniorhynchus (2.32), followed by Cx. vishnui (1.98) and Cx. pseudovishnui (0.71). All the larvae samples were negative for JEV. The mean number larvae of Cx. tritaeniorhynchus and Cx. pseudovishnui was negatively correlated with pH (r = - 0.45 and r = - 0.63) and turbidity (r = - 0.30 and r = - 0.37). In contrast, positive correlation was observed in case of Cx. quinquefasciatus. A total of 41 clinical samples were found positive for JEV by IgM ELISA. The rainfall was significantly associated with Japanese encephalitis incidence and showed positive correlation to disease transmission (p = 0.02, r = 0. 66). INTERPRETATION & CONCLUSION The findings showed the rapid dissemination of JEV within a population, facilitated by different species of Culex in the region. As JE is a vaccine-preventable disease, an immunization programme, an effective vector control strategy and application of standard hygiene practices in these endemic areas could result in a considerable reduction in morbidity and mortality due to JE.
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Affiliation(s)
| | | | | | | | | | - T N Dhole
- Department of Microbiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India
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Abstract
Background Despite its largely mountainous terrain for which this Himalayan country is a popular tourist destination, Nepal is now endemic for five major vector-borne diseases (VBDs), namely malaria, lymphatic filariasis, Japanese encephalitis, visceral leishmaniasis and dengue fever. There is increasing evidence about the impacts of climate change on VBDs especially in tropical highlands and temperate regions. Our aim is to explore whether the observed spatiotemporal distributions of VBDs in Nepal can be related to climate change. Methodology A systematic literature search was performed and summarized information on climate change and the spatiotemporal distribution of VBDs in Nepal from the published literature until December2014 following providing items for systematic review and meta-analysis (PRISMA) guidelines. Principal Findings We found 12 studies that analysed the trend of climatic data and are relevant for the study of VBDs, 38 studies that dealt with the spatial and temporal distribution of disease vectors and disease transmission. Among 38 studies, only eight studies assessed the association of VBDs with climatic variables. Our review highlights a pronounced warming in the mountains and an expansion of autochthonous cases of VBDs to non-endemic areas including mountain regions (i.e., at least 2,000 m above sea level). Furthermore, significant relationships between climatic variables and VBDs and their vectors are found in short-term studies. Conclusion Taking into account the weak health care systems and difficult geographic terrain of Nepal, increasing trade and movements of people, a lack of vector control interventions, observed relationships between climatic variables and VBDs and their vectors and the establishment of relevant disease vectors already at least 2,000 m above sea level, we conclude that climate change can intensify the risk of VBD epidemics in the mountain regions of Nepal if other non-climatic drivers of VBDs remain constant.
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Affiliation(s)
- Meghnath Dhimal
- Nepal Health Research Council (NHRC), Ministry of Health and Population Complex, Kathmandu, Nepal
- Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany
- Institute for Atmospheric and Environmental Sciences (IAU), Goethe University, Frankfurt am Main, Germany
- Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Frankfurt am Main, Germany
- * E-mail:
| | - Bodo Ahrens
- Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Frankfurt am Main, Germany
- Institute for Atmospheric and Environmental Sciences (IAU), Goethe University, Frankfurt am Main, Germany
| | - Ulrich Kuch
- Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Frankfurt am Main, Germany
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Abstract
Japanese encephalitis virus (JEV) is a zoonotic pathogen transmitted by the infectious bite of Culex mosquitoes. The virus causes the development of the disease Japanese encephalitis (JE) in a small proportion of those infected, predominantly affecting children in eastern and southern Asia. Annual JE incidence estimates range from 50,000–175,000, with 25%–30% of cases resulting in mortality. It is estimated that 3 billion people live in countries in which JEV is endemic. The virus exists in an enzootic transmission cycle, with mosquitoes transmitting JEV between birds as reservoir hosts and pigs as amplifying hosts. Zoonotic infection occurs as a result of spillover events from the main transmission cycle. The reservoir avian hosts include cattle egrets, pond herons, and other species of water birds belonging to the family Ardeidae. Irrigated rice fields provide an ideal breeding ground for mosquitoes and attract migratory birds, maintaining the transmission of JEV. Although multiple vaccines have been developed for JEV, they are expensive and require multiple doses to maintain efficacy and immunity. As humans are a “dead-end” host for the virus, vaccination of the human population is unlikely to result in eradication. Therefore, vector control of the principal mosquito vector, Culex tritaeniorhynchus, represents a more promising strategy for reducing transmission. Current vector control strategies include intermittent irrigation of rice fields and space spraying of insecticides during outbreaks. However, Cx. Tritaeniorhynchus is subject to heavy exposure to pesticides in rice fields, and as a result, insecticide resistance has developed. In recent years, significant advancements have been made in the potential use of the bacterial endosymbiont Wolbachia for mosquito biocontrol. The successful transinfection of Wolbachia strains from Drosophila flies to Aedes (Stegomyia) mosquitoes has resulted in the generation of “dengue-refractory” mosquito lines. The successful establishment of Wolbachia in wild Aedes aegypti populations has recently been demonstrated, and open releases in dengue-endemic countries are ongoing. This review outlines the current control methods for JEV in addition to highlighting the potential use of Wolbachia-based biocontrol strategies to impact transmission. JEV and dengue virus are both members of the Flavivirus genus, and the successful establishment of Drosophila Wolbachia strains in Cx. Tritaeniorhynchus, as the principal vector of JEV, is predicted to significantly impact JEV transmission.
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Affiliation(s)
- Claire L. Jeffries
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Thomas Walker
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
- * E-mail:
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Tian HY, Bi P, Cazelles B, Zhou S, Huang SQ, Yang J, Pei Y, Wu XX, Fu SH, Tong SL, Wang HY, Xu B. How environmental conditions impact mosquito ecology and Japanese encephalitis: an eco-epidemiological approach. Environ Int 2015; 79:17-24. [PMID: 25771078 DOI: 10.1016/j.envint.2015.03.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 02/02/2015] [Accepted: 03/01/2015] [Indexed: 06/04/2023]
Abstract
Japanese encephalitis (JE) is one of the major vector-borne diseases in Southeast Asia and the Western Pacific region, posing a threat to human health. In rural and suburban areas, traditional rice farming and intensive pig breeding provide an ideal environment for both mosquito development and the transmission of JEV among human beings. Combining surveillance data for mosquito vectors, human JE cases, and environmental conditions in Changsha, China, 2004-2009, generalized threshold models were constructed to project the mosquito and JE dynamics. Temperature and rainfall were found to be closely associated with mosquito density at 1, and 4month lag, respectively. The two thresholds, maximum temperature of 22-23°C for mosquito development and minimum temperature of 25-26°C for JEV transmission, play key roles in the ecology of JEV. The model predicts that, in the upper regime, a 1g/m(3) increase in absolute humidity would on average increase human cases by 68-84%. A shift in mosquito species composition in 2007 was observed, and possibly caused by a drought. Effective predictive models could be used in risk management to provide early warnings for potential JE transmission.
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Affiliation(s)
- Huai-Yu Tian
- State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing, People's Republic of China
| | - Peng Bi
- Discipline of Public Health, University of Adelaide, Adelaide, Australia
| | - Bernard Cazelles
- UMMISCO, UMI 209 IRD-UPMC, 93142 Bondy, France; Eco-Evolutionary Mathematic, IBENS UMR 8197, ENS, 75230 Paris Cedex 05, France
| | - Sen Zhou
- Ministry of Education Key Laboratory for Earth System Modelling, Center for Earth System Science, Tsinghua University, Beijing, People's Republic of China
| | - Shan-Qian Huang
- State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing, People's Republic of China
| | - Jing Yang
- State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing, People's Republic of China
| | - Yao Pei
- Ministry of Education Key Laboratory for Earth System Modelling, Center for Earth System Science, Tsinghua University, Beijing, People's Republic of China
| | - Xiao-Xu Wu
- State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing, People's Republic of China
| | - Shi-Hong Fu
- State Key Laboratory for Infectious Disease Prevention and Control (SKLID), Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, People's Republic of China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China
| | - Shi-Lu Tong
- School of Public Health and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland 4059, Australia
| | - Huan-Yu Wang
- State Key Laboratory for Infectious Disease Prevention and Control (SKLID), Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, People's Republic of China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People's Republic of China.
| | - Bing Xu
- State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing, People's Republic of China; Ministry of Education Key Laboratory for Earth System Modelling, Center for Earth System Science, Tsinghua University, Beijing, People's Republic of China; Department of Geography, University of Utah, Salt Lake City, UT 84112, USA.
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Misra BR, Gore M. Malathion Resistance Status and Mutations in Acetylcholinesterase Gene (Ace) in Japanese Encephalitis and Filariasis Vectors from Endemic Area in India. J Med Entomol 2015; 52:442-446. [PMID: 26334819 DOI: 10.1093/jme/tjv015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 01/21/2015] [Indexed: 06/05/2023]
Abstract
Japanese encephalitis (JE) and lymphatic filariasis (LF) are endemic in estern part of Uttar Pradesh in India and transmitted by Culex mosquitoes (Diptera: Culicidae). JE vaccination and mass drug administration for JE and LF management is being undertaken respectively. In addition to this, indoor residual spraying and fogging are used for the control of mosquito vectors. Organophosphate resistance in mosquito is dependent on alteration in acetylcholinesterase (Ace) gene. Hence, it is important to evaluate organophosphate resistance in Culex tritaeniorhynchus Giles (JE vector) and Culex quinquefasciatus Say (LF vector). The current study showed the presence of resistant populations and F331W mutation in Cx. tritaeniorhynchus and G119S mutation in Cx. quinquefasciatus insensitive Ace genes. Resistant populations of these two vectors increase the chances of spreading of resistance in the natural population and may cause failure of intervention programs that include organophosphates against these two vectors in future.
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Affiliation(s)
- Brij Ranjan Misra
- National Institute of Virology, GKP Unit, B.R.D. Medical College Campus, Gorakhpur 273013, India
| | - Milind Gore
- National Institute of Virology, GKP Unit, B.R.D. Medical College Campus, Gorakhpur 273013, India.
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Gao X, Zhou H, Liu H, Fu S, Wang H, Guo Z, Li X, Liang G. [Study on Spatial Dispersal and Migration Events of Japanese Encephalitis Virus]. Bing Du Xue Bao 2015; 31:264-268. [PMID: 26470532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
To explore the spatial distribution mechanism of Japanese encephalitis virus (JEV), PhyML v3.0 was used to build phylogenetic tree using JEV sequences in the dataset. PAUP v4.0 and Migrapyhla softz ware were then used to analyze the migration events. The results showed that a total of 95 migration events were observed during the dispersal of JEV throughout Asia. Further analysis revealed that Thailand, and several Chinese provinces (including Shandong, Shanghai, Sichuan and Yunnan), were the main migration sources of JEV. JEV spread from these migration sources as follows: from Thailand to Australia, Cambodia, Tibet and India; from Shanghai to eastern coastal Asian regions and Yunnan; from Shandong to Korea, Zhejiang, Hubei, Shanxi and Liaoning; from Sichuan mainly to inland regions of China, as well as Vietnam and Japan; and from Yunnan to Zhejiang. This study indicated that frequent migration events occurred during the dispersal of JEV in the Asia and Pacific regions, and that Thailand, Shandong, Shanghai, Sichuan and Yunnan were the sources of JEV dispersal.
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Mackenzie-Impoinvil L, Impoinvil DE, Galbraith SE, Dillon RJ, Ranson H, Johnson N, Fooks AR, Solomon T, Baylis M. Evaluation of a temperate climate mosquito, Ochlerotatus detritus (=Aedes detritus), as a potential vector of Japanese encephalitis virus. Med Vet Entomol 2015; 29:1-9. [PMID: 25087926 DOI: 10.1111/mve.12083] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 05/10/2014] [Accepted: 05/28/2014] [Indexed: 06/03/2023]
Abstract
The U.K. has not yet experienced a confirmed outbreak of mosquito-borne virus transmission to people or livestock despite numerous autochthonous epizootic and human outbreaks of mosquito-borne diseases on the European mainland. Indeed, whether or not British mosquitoes are competent to transmit arboviruses has not been established. Therefore, the competence of a local (temperate) British mosquito species, Ochlerotatus detritus (=Aedes detritus) (Diptera: Culicidae) for transmission of a member of the genus Flavivirus, Japanese encephalitis virus (JEV) as a model for mosquito-borne virus transmission was assessed. The JEV competence in a laboratory strain of Culex quinquefasciatus (Diptera: Culicidae), a previously incriminated JEV vector, was also evaluated as a positive control. Ochlerotatus detritus adults were reared from field-collected juvenile stages. In oral infection bioassays, adult females developed disseminated infections and were able to transmit virus as determined by the isolation of virus in saliva secretions. When pooled at 7-21 days post-infection, 13% and 25% of O. detritus were able to transmit JEV when held at 23 °C and 28 °C, respectively. Similar results were obtained for C. quinquefasciatus. To our knowledge, this study is the first to demonstrate that a British mosquito species, O. detritus, is a potential vector of an exotic flavivirus.
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Affiliation(s)
- L Mackenzie-Impoinvil
- Brain Infections Group, Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, U.K
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Rajavel AR, Kumar NP, Natarajan R, Vanamail P, Rathinakumar A, Jambulingam P. Morphological and molecular characterization of the ecological, biological and behavioural variants of the JE vector Culex tritaeniorhynchus: an assessment of its taxonomic status. J Vector Borne Dis 2015; 52:40-51. [PMID: 25815866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
BACKGROUND & OBJECTIVES Culex tritaeniorhynchus (Diptera: Culicidae), an important vector of Japanese encephalitis belongs to the Culex vishnui subgroup which includes two other vector species namely, Cx. Vishnui and Cx. pseudovishnui. Many varieties and types of Cx. tritaeniorhynchus have been reported, besides populations that exhibit behavioural and biological differences. This study was undertaken to find out whether Cx. tritaeniorhynchus populations exhibiting behavioural and biological variations, and those from different geographical areas, are comprised of more than one taxon or belong to a single taxon. METHODS Morphological characterization was done by examining 153 morphological and morphometric characters in the larval (75), pupal (60) and adult stages (18) of five geographical populations of Cx. tritaeniorhynchus. Molecular characterization was done by PCR amplification of mitochondrial cytochrome c oxidase (COI) gene sequences (DNA barcodes) and another hypervariable genetic marker, the ribosomal DNA (16S). One-way ANOVA, principal component analysis (PCA) and discriminant factor analysis (DFA) were done for statistical analyses using the statistical package SPSS IBM version 19.0. RESULTS Morphological characterization showed that no intraspecific differentiation can be made among the five geographical populations of Cx. tritaeniorhynchus. Molecular characterization done by DNA barcoding also showed that the COI sequences of all the five populations of Cx. tritaeniorhynchus grouped into a single taxonomic clade plus the genetic differentiation among these was non-significant and the overall gene flow among the populations was very high. Analysis of the ribosomal DNA also confirmed that the Cx. tritaeniorhynchus populations belonged to a single taxon. INTERPRETATION & CONCLUSION Culex tritaeniorhynchus is a taxon that does not involve cryptic species.
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Affiliation(s)
- A R Rajavel
- Vector Control Research Centre (ICMR), Indira Nagar, Puducherry, India
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Japanese Encephalitis Vaccines: WHO position paper – February 2015. Wkly Epidemiol Rec 2015; 90:69-87. [PMID: 25726573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
MESH Headings
- Animals
- Asymptomatic Infections/epidemiology
- Chlorocebus aethiops
- Cost-Benefit Analysis
- Encephalitis Virus, Japanese/immunology
- Encephalitis Virus, Japanese/pathogenicity
- Encephalitis, Japanese/diagnosis
- Encephalitis, Japanese/immunology
- Encephalitis, Japanese/prevention & control
- Encephalitis, Japanese/transmission
- Humans
- Immunocompromised Host/immunology
- Japanese Encephalitis Vaccines/administration & dosage
- Japanese Encephalitis Vaccines/adverse effects
- Japanese Encephalitis Vaccines/economics
- Japanese Encephalitis Vaccines/immunology
- Population Surveillance
- Vaccines, Attenuated/administration & dosage
- Vaccines, Attenuated/adverse effects
- Vaccines, Attenuated/immunology
- Vaccines, Inactivated/administration & dosage
- Vaccines, Inactivated/adverse effects
- Vaccines, Inactivated/immunology
- Vero Cells
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Kim H, Cha GW, Jeong YE, Lee WG, Chang KS, Roh JY, Yang SC, Park MY, Park C, Shin EH. Detection of Japanese encephalitis virus genotype V in Culex orientalis and Culex pipiens (Diptera: Culicidae) in Korea. PLoS One 2015; 10:e0116547. [PMID: 25658839 PMCID: PMC4319795 DOI: 10.1371/journal.pone.0116547] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 10/24/2014] [Indexed: 11/18/2022] Open
Abstract
Japanese encephalitis virus (JEV) causes significant viral encephalitis and is distributed throughout the Asian countries. The virus is known to be transmitted by Culex tritaeniorhynchus, which mainly breeds in rice paddies in Korea. In this study, we investigated the presence of other mosquito species that can transmit JEV as a second or regional vector. We selected five cities where patients have experienced JE in the last 5 years as mosquito-collecting locations and subdivided them into four collection sites according to the mosquito habitats (cowshed, downtown area, forest, and swamp). Mosquitoes were caught using the BG-Sentinel trap, CDC black-light trap, Fay-Prince trap, and Gravid trap. A total of 993 pools from 22,774 mosquitoes were prepared according to their species, collection date, and site. We performed a SYBR Green 1-based real-time RT-PCR assay to detect JEV from the mosquito pools. A total of six JEV-positive pools were detected from Culex orientalis and Culex pipiens caught in the Gangwon-do and Gyeonngi-do provinces. All the detected JEVs were revealed as genotype V by phylogenetic analysis of the envelope gene. Our findings confirm that a new genotype of JEV was introduced in Korea and suggest that two mosquito species may play a role in JEV transmission.
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Affiliation(s)
- Hyunwoo Kim
- Division of Medical Entomology, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
- Department of Agricultural Biotechnology, Seoul National University, Seoul, South Korea
| | - Go-Woon Cha
- Division of Arboviruses, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
| | - Young Eui Jeong
- Division of Arboviruses, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
- Department of Biomedical Sciences, Graduate School of Hallym University, Chuncheon, South Korea
| | - Wook-Gyo Lee
- Division of Medical Entomology, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
| | - Kyu Sik Chang
- Division of Medical Entomology, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
| | - Jong Yul Roh
- Division of Medical Entomology, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
| | - Sung Chan Yang
- Division of Medical Entomology, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
| | - Mi Yeoun Park
- Division of Medical Entomology, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
| | - Chan Park
- Division of Arboviruses, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
| | - E-Hyun Shin
- Division of Medical Entomology, Center for Immunology and Pathology, Korea National Institute of Health, Cheongju, South Korea
- * E-mail:
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Daep CA, Muñoz-Jordán JL, Eugenin EA. Flaviviruses, an expanding threat in public health: focus on dengue, West Nile, and Japanese encephalitis virus. J Neurovirol 2014; 20:539-60. [PMID: 25287260 PMCID: PMC4331079 DOI: 10.1007/s13365-014-0285-z] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/01/2014] [Accepted: 08/26/2014] [Indexed: 10/24/2022]
Abstract
The flaviviruses dengue, West Nile, and Japanese encephalitis represent three major mosquito-borne viruses worldwide. These pathogens impact the lives of millions of individuals and potentially could affect non-endemic areas already colonized by mosquito vectors. Unintentional transport of infected vectors (Aedes and Culex spp.), traveling within endemic areas, rapid adaptation of the insects into new geographic locations, climate change, and lack of medical surveillance have greatly contributed to the increase in flaviviral infections worldwide. The mechanisms by which flaviviruses alter the immune and the central nervous system have only recently been examined despite the alarming number of infections, related deaths, and increasing global distribution. In this review, we will discuss the expansion of the geographic areas affected by flaviviruses, the potential threats to previously unaffected countries, the mechanisms of pathogenesis, and the potential therapeutic interventions to limit the devastating consequences of these viruses.
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Affiliation(s)
- Carlo Amorin Daep
- Public Health Research Institute (PHRI), Rutgers New Jersey Medical School, Rutgers the State University of New Jersey, Newark, NJ, USA
- Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers the State University of New Jersey, Newark, NJ, USA
| | - Jorge L. Muñoz-Jordán
- Centers for Disease Control and Prevention Dengue Branch, 1324 Cañada Street, San Juan, PR 00971
| | - Eliseo Alberto Eugenin
- Public Health Research Institute (PHRI), Rutgers New Jersey Medical School, Rutgers the State University of New Jersey, Newark, NJ, USA
- Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers the State University of New Jersey, Newark, NJ, USA
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Su CL, Yang CF, Teng HJ, Lu LC, Lin C, Tsai KH, Chen YY, Chen LY, Chang SF, Shu PY. Molecular epidemiology of Japanese encephalitis virus in mosquitoes in Taiwan during 2005-2012. PLoS Negl Trop Dis 2014; 8:e3122. [PMID: 25275652 PMCID: PMC4183467 DOI: 10.1371/journal.pntd.0003122] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 07/16/2014] [Indexed: 11/18/2022] Open
Abstract
Japanese encephalitis (JE) is a mosquito-borne zoonotic disease caused by the Japanese encephalitis virus (JEV). Pigs and water birds are the main amplifying and maintenance hosts of the virus. In this study, we conducted a JEV survey in mosquitoes captured in pig farms and water bird wetland habitats in Taiwan during 2005 to 2012. A total of 102,633 mosquitoes were collected. Culex tritaeniorhynchus was the most common mosquito species found in the pig farms and wetlands. Among the 26 mosquito species collected, 11 tested positive for JEV by RT-PCR, including Cx. tritaeniorhynchus, Cx. annulus, Anopheles sinensis, Armigeres subalbatus, and Cx. fuscocephala. Among those testing positive, Cx. tritaeniorhynchus was the predominant vector species for the transmission of JEV genotypes I and III in Taiwan. The JEV infection rate was significantly higher in the mosquitoes from the pig farms than those from the wetlands. A phylogenetic analysis of the JEV envelope gene sequences isolated from the captured mosquitoes demonstrated that the predominant JEV genotype has shifted from genotype III to genotype I (GI), providing evidence for transmission cycle maintenance and multiple introductions of the GI strains in Taiwan during 2008 to 2012. This study demonstrates the intense JEV transmission activity in Taiwan, highlights the importance of JE vaccination for controlling the epidemic, and provides valuable information for the assessment of the vaccine's efficacy. Japanese encephalitis (JE) is a vector-borne zoonotic disease transmitted by the bite of a Japanese encephalitis virus (JEV) infected mosquito. Japanese encephalitis is an endemic disease in Taiwan. Before 2008, all known JEV isolates collected in Taiwan belonged to Genotype III of JEV. Genotype I JEV strains were first found in northern Taiwan in 2008. In this study, we conducted a survey of JEV in mosquitoes during 2005–2012. A total of 102,633 mosquitoes were collected from pig farms and wetlands. Among the 26 mosquito species collected, 11 tested JEV positive by RT-PCR, including Cx. tritaeniorhynchus, Cx. annulus and An. sinensis. Cx. tritaeniorhynchus was the predominant vector species for transmission of JEV in Taiwan. The JEV infection rate of the mosquitoes captured on the pig farms was significantly higher than the rate of those captured in the wetlands, indicating that pigs played an important role in amplifying JEV. A phylogenetic analysis of the envelope gene sequences of JEV isolated from the mosquitoes demonstrated that the predominant JEV genotype shifted from genotype III to genotype I (GI), providing evidence for multiple introductions and transmission cycle maintenance of GI strains in Taiwan during 2008–2012.
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Affiliation(s)
- Chien-Ling Su
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
| | - Cheng-Fen Yang
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
| | - Hwa-Jen Teng
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
| | - Liang-Chen Lu
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
| | - Cheo Lin
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
| | - Kun-Hsien Tsai
- Institute of Environmental Health, College of Public Health, National Taiwan University, Taipei, Taiwan
- Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan
- Infectious Diseases Research and Education Center, Ministry of Health and Welfare and National Taiwan University, Taipei, Taiwan, Republic of China
| | - Yu-Yu Chen
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
| | - Li-Yu Chen
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
| | - Shu-Fen Chang
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
| | - Pei-Yun Shu
- Center for Research, Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taiwan, Republic of China
- * E-mail:
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Khan SU, Salje H, Hannan A, Islam MA, Bhuyan AAM, Islam MA, Rahman MZ, Nahar N, Hossain MJ, Luby SP, Gurley ES. Dynamics of Japanese encephalitis virus transmission among pigs in Northwest Bangladesh and the potential impact of pig vaccination. PLoS Negl Trop Dis 2014; 8:e3166. [PMID: 25255286 PMCID: PMC4177832 DOI: 10.1371/journal.pntd.0003166] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 08/04/2014] [Indexed: 11/19/2022] Open
Abstract
Background Japanese encephalitis (JE) virus infection can cause severe disease in humans, resulting in death or permanent neurologic deficits among survivors. Studies indicate that the incidence of JE is high in northwestern Bangladesh. Pigs are amplifying hosts for JE virus (JEV) and a potentially important source of virus in the environment. The objectives of this study were to describe the transmission dynamics of JEV among pigs in northwestern Bangladesh and estimate the potential impact of vaccination to reduce incidence among pigs. Methodology/Principal Findings We conducted a comprehensive census of pigs in three JE endemic districts and tested a sample of them for evidence of previous JEV infection. We built a compartmental model to describe JEV transmission dynamics in this region and to estimate the potential impact of pig vaccination. We identified 11,364 pigs in the study area. Previous JEV infection was identified in 30% of pigs with no spatial differences in the proportion of pigs that were seropositive across the study area. We estimated that JEV infects 20% of susceptible pigs each year and the basic reproductive number among pigs was 1.2. The model suggest that vaccinating 50% of pigs each year resulted in an estimated 82% reduction in annual incidence in pigs. Conclusions/Significance The widespread distribution of historic JEV infection in pigs suggests they may play an important role in virus transmission in this area. Future studies are required to understand the contribution of pig infections to JE risk in humans and the potential impact of pig vaccination on human disease. Japanese encephalitis (JE) virus infection can cause severe neurological disease in man. More JE cases are seen in northwestern districts in Bangladesh. Pigs are the most common amplifying host of the virus and can act as a potential environmental source. We conducted a comprehensive census of pigs in three JE endemic districts and tested a sample of them for evidence of previous JEV infection. We built a compartmental model to describe JEV transmission dynamics in this region and to estimate the potential impact of pig vaccination. We identified 11,364 pigs in our study area, mostly raised in backyards. About 30% of the pigs had evidence of previous JE virus infection. Our model suggests that vaccinating 50% of pigs each year resulted in an estimated 82% reduction in annual incidence in pigs. Pigs in northwestern Bangladesh may play a significant role in JE virus transmission. JE incidence may be substantially reduced through reasonable pig vaccination coverage.
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Affiliation(s)
- Salah Uddin Khan
- Centre for Communicable Diseases, i,cddr,b, Dhaka, Bangladesh
- College of Public Health and Health Professions - Department of Environmental and Global Health, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| | - Henrik Salje
- Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - A. Hannan
- Department of Livestock Services, Ministry of Fisheries and Livestock, Dhaka, Bangladesh
| | | | | | | | - M. Ziaur Rahman
- Centre for Communicable Diseases, i,cddr,b, Dhaka, Bangladesh
| | - Nazmun Nahar
- Centre for Communicable Diseases, i,cddr,b, Dhaka, Bangladesh
| | | | - Stephen P. Luby
- Centre for Communicable Diseases, i,cddr,b, Dhaka, Bangladesh
- Global Disease Detection Branch, Division of Global Health Protection, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Emily S. Gurley
- Centre for Communicable Diseases, i,cddr,b, Dhaka, Bangladesh
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Chiang WW, Chuang CK, Chao M, Chen WJ. Cell type-dependent RNA recombination frequency in the Japanese encephalitis virus. Biomed Res Int 2014; 2014:471323. [PMID: 25165704 PMCID: PMC4140105 DOI: 10.1155/2014/471323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Accepted: 07/02/2014] [Indexed: 11/17/2022]
Abstract
Japanese encephalitis virus (JEV) is one of approximately 70 flaviviruses, frequently causing symptoms involving the central nervous system. Mutations of its genomic RNA frequently occur during viral replication, which is believed to be a force contributing to viral evolution. Nevertheless, accumulating evidences show that some JEV strains may have actually arisen from RNA recombination between genetically different populations of the virus. We have demonstrated that RNA recombination in JEV occurs unequally in different cell types. In the present study, viral RNA fragments transfected into as well as viral RNAs synthesized in mosquito cells were shown not to be stable, especially in the early phase of infection possibly via cleavage by exoribonuclease. Such cleaved small RNA fragments may be further degraded through an RNA interference pathway triggered by viral double-stranded RNA during replication in mosquito cells, resulting in a lower frequency of RNA recombination in mosquito cells compared to that which occurs in mammalian cells. In fact, adjustment of viral RNA to an appropriately lower level in mosquito cells prevents overgrowth of the virus and is beneficial for cells to survive the infection. Our findings may also account for the slower evolution of arboviruses as reported previously.
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Affiliation(s)
- Wei-Wei Chiang
- Division of Microbiology, Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan
| | - Ching-Kai Chuang
- Division of Microbiology, Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546-0312, USA
| | - Mei Chao
- Division of Microbiology, Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan
- Department of Microbiology and Immunology, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan
| | - Wei-June Chen
- Division of Microbiology, Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan
- Department of Public Health and Parasitology, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan
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Cleton N, Koopmans M, Braks M, Van Maanen K, Reusken C. [Japanese encephalitis in Southern Europe]. Tijdschr Diergeneeskd 2014; 139:20-25. [PMID: 25090898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In 2012, a fragment of the Japanese encephalitis virus (JEV) genome was isolated from a pool of Culex pipiens mosquitoes caught in 2010 and 2011 in Northern Italy. JEV has a broad geographical distribution in South and Southeast Asia and Oceania, and is the most important cause of viral encephalitis in Asia in humans and also causes encephalitis in horses and fertility problems in pigs. However, recently isolated JEV genome fragments in mosquitoes in Italy could be an indication of repeated introduction of JEV, enzootic circulation of JEV or a related virus in Southern Europe. Until more information is available, Japanese encephalitis remains a travel-related infectious disease for travellers to JEV endemic and epidemic areas outside of Europe.
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Fox A, Whitehead S, Anders KL, Hoa LNM, Mai LQ, Thai PQ, Yen NT, Duong TN, Thoang DD, Farrar J, Wertheim H, Simmons C, Hien NT, Horby P. Investigation of dengue and Japanese encephalitis virus transmission in Hanam, Viet Nam. Am J Trop Med Hyg 2014; 90:892-896. [PMID: 24615123 PMCID: PMC4015583 DOI: 10.4269/ajtmh.13-0077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 11/14/2013] [Indexed: 11/23/2022] Open
Abstract
This study investigated whether a large dengue epidemic that struck Hanoi in 2009 also affected a nearby semirural area. Seroconversion (dengue virus-reactive immunoglobulin G enzyme-linked immunosorbent assay) was high during 2009 compared with 2008, but neutralization assays showed that it was caused by both dengue virus and Japanese encephalitis virus infections. The findings highlight the importance of continued Japanese encephalitis virus vaccination and dengue surveillance.
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Affiliation(s)
- Annette Fox
- Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Viet Nam; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom; National Institute of Allergy and Infectious Diseases, Bethesda, Maryland; National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; Hanam Centre for Preventive Medicine, Hanam, Viet Nam
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Abstract
Japanese encephalitis (JE) is the most common form of viral encephalitis that appears in the form of frequent epidemics of brain fever throughout Southeast Asia, China and India. The disease is caused by a Flavivirus named Japanese encephalitis virus that is spread to humans by mosquitoes. An internationally approved mouse brain-derived inactivated vaccine has been available that is relatively expensive, gives immunity of uncertain duration and is not completely safe. Cell culture-derived inactivated and attenuated JE vaccines are in use in China, but these are not produced as per the norms acceptable in most countries. Several new promising JE vaccine candidates have been developed, some of which are under different stages of clinical evaluation. These new candidate JE vaccines have the potential to generate long-lasting immunity at low cost.
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Affiliation(s)
- Kaushik Bharati
- Virology laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110 067, India.
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Bai Y, Xu Z, Zhang J, Mao D, Luo C, He Y, Liang G, Lu B, Bisesi MS, Sun Q, Xu X, Yang W, Liu Q. Regional impact of climate on Japanese encephalitis in areas located near the three gorges dam. PLoS One 2014; 9:e84326. [PMID: 24404159 PMCID: PMC3880291 DOI: 10.1371/journal.pone.0084326] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 11/20/2013] [Indexed: 11/18/2022] Open
Abstract
Background In this study, we aim to identify key climatic factors that are associated with the transmission of Japanese encephalitis virus in areas located near the Three Gorges Dam, between 1997 and 2008. Methods We identified three geographical regions of Chongqing, based on their distance from the Three Gorges Dam. Collectively, the three regions consisted of 12 districts from which study information was collected. Zero-Inflated Poisson Regression models were run to identify key climatic factors of the transmission of Japanese encephalitis virus for both the whole study area and for each individual region; linear regression models were conducted to examine the fluctuation of climatic variables over time during the construction of the Three Gorges Dam. Results Between 1997 and 2008, the incidence of Japanese encephalitis decreased throughout the entire city of Chongqing, with noticeable variations taking place in 2000, 2001 and 2006. The eastern region, which is closest to the Three Gorges Dam, suffered the highest incidence of Japanese encephalitis, while the western region experienced the lowest incidence. Linear regression models revealed that there were seasonal fluctuations of climatic variables during this period. Zero-Inflated Poisson Regression models indicated a significant positive association between temperature (with a lag of 1 and 3 months) and Japanese encephalitis incidence, and a significant negative association between rainfall (with a lag of 0 and 4 months) and Japanese encephalitis incidence. Conclusion The spatial and temporal trends of Japanese encephalitis incidence that occurred in the City of Chongqing were associated with temperature and rainfall. Seasonal fluctuations of climatic variables during this period were also observed. Additional studies that focus on long-term data collection are needed to validate the findings of this study and to further explore the effects of the Three Gorges Dam on Japanese encephalitis and other related diseases.
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Affiliation(s)
- Yuntao Bai
- Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, Ohio, United States of America
| | - Zhiguang Xu
- Department of Statistics, The Ohio State University, Columbus, Ohio, United States of America
| | - Jing Zhang
- Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Deqiang Mao
- Chongqing Center for Disease Control and Prevention, Chongqing, China
| | - Chao Luo
- Wanzhou District Control of Diseases Prevention and Control, Chongqing, China
| | - Yuanyuan He
- Yichang Center for Disease Control and Prevention, Yichang, Hubei Province, China
| | - Guodong Liang
- State Key Laboratory for Infectious Diseases Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Bo Lu
- Division of Biostatistics, College of Public Health, The Ohio State University, Columbus, Ohio, United States of America
| | - Michael S. Bisesi
- Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, Ohio, United States of America
| | - Qinghua Sun
- Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, Ohio, United States of America
| | - Xinyi Xu
- Department of Statistics, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail: (QL); (WY); (XX)
| | - Weizhong Yang
- Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China
- * E-mail: (QL); (WY); (XX)
| | - Qiyong Liu
- Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China
- Department of Vector Biology and Control, State Key Laboratory for Infectious Diseases Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- * E-mail: (QL); (WY); (XX)
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Dhiman S, Rabha B, Talukdar P, Das N, Yadav K, Baruah I, Singh L, Veer V. DDT & deltamethrin resistance status of known Japanese encephalitis vectors in Assam, India. Indian J Med Res 2013; 138:988-94. [PMID: 24521646 PMCID: PMC3978992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND & OBJECTIVE Japanese encephalitis (JE) outbreaks are common in Assam, northeastern State of India. Information on resistance in known JE vectors in the affected area is important for effective control measures. This study was undertaken to determine the species abundance of JE vectors endemic to Sibsagar district of Assam, and their susceptibility against DDT and deltamethrin. METHODS Adult mosquitoes were collected using CDC light trap and aspirators from human dwellings from 13 endemic villages falling under three Primary Health Centres. Collected mosquitoes were identified and unfed female mosquitoes were used for DDT and deltamethrin sensitivity bioassay. The bioassay was performed following WHO protocol using standard susceptibility test kit. Knockdown time (KDT) was monitored at every 10 minutes intervals, whereas mortalities were recorded 24 h post-exposure. Vector density and resistance status were mapped using geographic information system (GIS) technique. RESULTS A total of 7655 mosquitoes were sampled under three genera, i.e. Anopheles, Culex and Mansonia, and nine species, the JE vector Cx. vishnui group (31.78%) was the most predominant species, followed by Ma. uniformis (16.81%) and Ma. indiana (16.45%). All vector species were suspected to be resistant to DDT and sensitive to deltamethrin, except Ma. indiana, which was suspected to deltamethrin resistant. The KDT50 and KDT95 values of vector mosquitoes for DDT were significantly higher as compared to deltamethrin. The probit model used to estimate KDT50 and KDT95 values did not display normal distribution of percentage knockdown with time for all the vectors tested for DDT and deltamethrin, except for Ma. indiana for deltamethrin assay and Cx. gelidus for the DDT assay. INTERPRETATION & CONCLUSION Differences in insecticide resistance status were observed between insecticides and vector species. The results of this study provided baseline data on insecticide resistance in known JE vectors of Sibsagar, Assam. The maps generated may allow better communication in control operations and comparison of changes in susceptibility status of these vectors over time.
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Affiliation(s)
- Sunil Dhiman
- Medical Entomology Division, Defence Research Laboratory, Tezpur, India
| | - Bipul Rabha
- Medical Entomology Division, Defence Research Laboratory, Tezpur, India
| | - P.K. Talukdar
- Medical Entomology Division, Defence Research Laboratory, Tezpur, India
| | - N.G. Das
- Medical Entomology Division, Defence Research Laboratory, Tezpur, India
| | - Kavita Yadav
- Medical Entomology Division, Defence Research Laboratory, Tezpur, India
| | - Indra Baruah
- Medical Entomology Division, Defence Research Laboratory, Tezpur, India
| | - Lokendra Singh
- Medical Entomology Division, Defence Research Laboratory, Tezpur, India
| | - Vijay Veer
- Medical Entomology Division, Defence Research Laboratory, Tezpur, India
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Gao X, Liu H, Wang H, Fu S, Guo Z, Liang G. Southernmost Asia is the source of Japanese encephalitis virus (genotype 1) diversity from which the viruses disperse and evolve throughout Asia. PLoS Negl Trop Dis 2013; 7:e2459. [PMID: 24069502 PMCID: PMC3777887 DOI: 10.1371/journal.pntd.0002459] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Accepted: 08/14/2013] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Although a previous study predicted that Japanese encephalitis virus (JEV) originated in the Malaysia/Indonesia region, the virus is known to circulate mainly on the Asian continent. However, there are no reported systematic studies that adequately define how JEV then dispersed throughout Asia. METHODOLOGY/PRINCIPAL FINDINGS In order to understand the mode of JEV dispersal throughout the entire Asian continent and the factors that determine the dispersal characteristics of JEV, a phylogenetic analysis using Bayesian Markov chain Monte Carlo simulations was conducted on all available JEV E gene sequences in GenBank, plus strains recently isolated in China. Here we demonstrate for the first time that JEV lineages can be divided into four endemic cycles, comprising southern Asia, eastern coastal Asia, western Asia, and central Asia. The isolation places of the viruses in each endemic cycle were geographically independent regardless of years, vectors, and hosts of isolation. Following further analysis, we propose that the southernmost region (Thailand, Vietnam, and Yunnan Province, China) was the source of JEV transmission to the Asian continent following its emergence. Three independent transmission routes from the south to north appear to define subsequent dispersal of JEV. Analysis of JEV population dynamics further supports these concepts. CONCLUSIONS/SIGNIFICANCE These results and their interpretation provide new insights into our understanding of JEV evolution and dispersal and highlight its potential for introduction into non-endemic areas.
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Affiliation(s)
- Xiaoyan Gao
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China
| | - Hong Liu
- School of Life Sciences, Shandong University of Technology, Zibo, Shandong, People's Republic of China
| | - Huanyu Wang
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China
| | - Shihong Fu
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China
| | - Zhenyang Guo
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China
| | - Guodong Liang
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, People's Republic of China
- * E-mail:
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